The Ultimate Guide to Sleep: The Science of Better Sleep, Recovery and Healthy Ageing
Sleep is an active biological process, not simply time switched off. While you sleep, the brain cycles through distinct stages that support memory, attention and emotional balance, and the body regulates hormones, metabolism and immune activity. Most adults need around seven hours or more a night, but the right amount varies, and regularity and quality matter as well as duration. Short-term poor sleep is common and usually improves with steady habits, especially a regular wake time, daylight in the morning and a calmer evening. Sleep problems that persist for months, affect daily life or come with loud snoring, pauses in breathing or excessive daytime sleepiness need assessment by a GP.
At a glance
Two systems control sleep. Sleep pressure builds the longer you are awake, and an internal body clock, set mainly by light, decides when sleep comes most easily.
Sleep has stages. Each night you move through cycles of lighter sleep, deep slow-wave sleep and REM sleep, and each plays a part in recovery.
Duration guidance is a starting point. Most adults do best with seven or more hours, but feeling refreshed and alert during the day is a better guide than a fixed number.
Regularity matters. A consistent wake time and daylight early in the day help keep the body clock stable.
Screens are one factor among many. Bright light and stimulating content late in the evening can delay sleep, but stress, caffeine, alcohol, pain and irregular schedules can matter as much or more.
Persistent insomnia has an effective treatment. Cognitive behavioural therapy for insomnia (CBT-I) is the recommended first-line treatment.
Some symptoms need medical advice. Loud snoring with pauses in breathing, falling asleep unintentionally during the day, or insomnia lasting months should be discussed with a GP.
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How sleep works
Sleep is an active process
For much of history, sleep was thought of as a passive state, the brain simply powering down. Recordings of brain activity tell a different story. During sleep the brain moves through organised patterns of electrical activity, hormone release changes, and networks involved in memory and emotion remain busy. [1]
Sleep is regulated by two interacting systems, often described as the two-process model. [2]
Sleep pressure: the homeostatic drive
The longer you are awake, the stronger your drive to sleep becomes. This build-up is called homeostatic sleep pressure. One of the chemical signals involved is adenosine, a by-product of the brain's energy use that accumulates during waking hours and promotes sleepiness. Sleep, particularly deep sleep, dissipates this pressure. [2, 3]
Caffeine works largely by blocking adenosine receptors, which is why it can mask sleepiness without removing the underlying need for sleep. [3]
The circadian rhythm: the timing drive
Alongside sleep pressure, an internal clock runs on a cycle of roughly 24 hours. It makes you more alert at some times of day and sleepier at others, regardless of how long you have been awake. [2]
Most people feel sleepiest when both systems line up: sleep pressure is high late in the evening, and the body clock is moving into its biological night. The two processes also explain common experiences, such as a second wind late in the evening, or feeling wide awake in the middle of the night after a long-haul flight.
The stages of sleep
Non-REM and REM sleep
Sleep is divided into non-rapid eye movement (non-REM) sleep, which has three stages, and rapid eye movement (REM) sleep. These stages are defined from brain-wave, eye-movement and muscle recordings in sleep laboratories. [1]
Stage | What happens | Why it matters |
N1 | The transition from waking to sleep. Brain waves slow, muscles relax, and you can be woken easily. It usually lasts only a few minutes. | Light sleep that acts as a gateway into deeper stages. |
N2 | Established light sleep. Heart rate and body temperature fall, and the brain produces characteristic bursts of activity called sleep spindles and K-complexes. N2 makes up the largest share of the night. | Linked to memory processing and to stable, continuous sleep. |
N3 | Deep, slow-wave sleep. Brain waves are large and slow, and it is hardest to wake someone from this stage. | Associated with physical recovery, release of growth hormone and the recovery from sleep pressure. |
REM | The brain becomes highly active, the eyes move rapidly and most vivid dreaming occurs. Most voluntary muscles are temporarily paralysed. | Associated with emotional processing and some forms of memory. |
Source: Patel et al. [1]
These links describe what the research associates with each stage. No stage performs a single isolated job, and the stages work together across the night.
How sleep cycles through the night
A healthy night usually includes four to six cycles, each lasting roughly 90 minutes. Deep N3 sleep is concentrated in the first half of the night, while REM periods become longer in the second half, towards morning. [1] This is one reason why cutting sleep short at the end of the night tends to reduce REM sleep, while going to bed very late can shift when deep sleep occurs.
Brief awakenings and arousals are a normal part of sleep, and they become more frequent with age. Most are so short that they are not remembered. [4]
Your body clock
The suprachiasmatic nucleus
The body's master clock sits in a small region of the brain called the suprachiasmatic nucleus (SCN), in the hypothalamus. It coordinates timing signals for sleep, hormone release, body temperature, digestion and many other processes. [5]
Light: the clock's strongest signal
The internal clock does not run at exactly 24 hours, so it needs daily resetting. Light is the strongest signal. Specialised light-sensitive cells in the retina, which contain a pigment called melanopsin and are particularly sensitive to blue light, are the main direct link from the eye to the SCN. [5]
Timing matters:
Daylight, especially outdoors and earlier in the day, helps keep the body clock stable, because light is the clock's main daily timing signal. [5]
Bright light late in the evening and at night can delay the clock and suppress melatonin, making it harder to fall asleep at your usual time. [6, 7]
Melatonin
Melatonin is a hormone made by the pineal gland under the control of the body clock. It is produced in darkness, typically at night, and light at night stops its production. [7] Melatonin acts as a signal of biological night rather than as a sleeping pill.
Cortisol's normal daily rhythm
Cortisol, often called a stress hormone, also follows a daily rhythm. It is usually at its lowest around midnight and highest in the early morning. [8] On top of this, cortisol rises sharply in the first 30 to 45 minutes after waking. This is called the cortisol awakening response, and it is a normal part of preparing the body for the day. [9]
Chronotypes
People differ in their natural timing, known as chronotype. Some are morning types who wake early and feel sharp in the morning. Others are evening types who feel more alert late in the day and struggle with early starts. Most people sit somewhere in between.
Social jet lag, shift work and travel
When work, school or social schedules force a different sleep pattern from your body clock, the mismatch is sometimes called social jet lag, for example sleeping much later at weekends than on workdays. In a large survey study, greater social jet lag was associated with a higher body mass index, although this kind of study cannot show cause and effect. [10]
Shift work and travel across time zones create larger mismatches. The International Agency for Research on Cancer classifies night shift work as probably carcinogenic to humans. [11] This classification describes the strength of evidence for a hazard, not the size of the risk for any individual.
An example 24-hour pattern
The table shows a typical pattern for someone with an intermediate chronotype who wakes around 7am. It is an illustration, not a target, and individual timing varies by several hours.
Approximate time | What tends to happen |
Waking (around 7am) | Cortisol rises sharply in the first 30 to 45 minutes after waking |
Morning and daytime | Daylight helps anchor the body clock; sleep pressure begins to build |
Evening | As it gets dark, melatonin production starts; sleep pressure is high |
Around midnight | Cortisol is at its lowest |
Night | Melatonin is produced in darkness; deep sleep is concentrated in the first half of the night |
Sources: Balbo et al., Stalder et al., Tonon et al. and StatPearls. [8, 9, 7, 1]
How much sleep do you need?
Recommendations by age
Expert panels recommend that adults aged 18 to 60 regularly sleep for seven hours or more a night. [12] The National Sleep Foundation's recommended ranges are shown below. [13]
Age group | Recommended range per 24 hours |
Newborns (0–3 months) | 14–17 hours |
Infants (4–11 months) | 12–15 hours |
Toddlers (1–2 years) | 11–14 hours |
Pre-school (3–5 years) | 10–13 hours |
School age (6–13 years) | 9–11 hours |
Teenagers (14–17 years) | 8–10 hours |
Young adults (18–25 years) | 7–9 hours |
Adults (26–64 years) | 7–9 hours |
Older adults (65+ years) | 7–8 hours |
Source: National Sleep Foundation. [13]
Need, opportunity, duration and quality
These terms are often confused:
Sleep need is the amount your body requires to function well. It varies between people.
Sleep opportunity is the time you allow for sleep, from lights out to getting up.
Sleep duration is how long you actually sleep within that opportunity.
Sleep quality reflects how continuous and restorative sleep feels, including how long it takes to fall asleep and how often you wake.
Some people who feel they sleep poorly are not allowing enough opportunity for sleep. Others allow plenty of time but sleep poorly within it, which is a different problem.
Why recommendations are not prescriptions
The recommended ranges are based on population research and expert consensus. They are useful guidance, but some people function well at the lower end and others need more. The most practical test is how you feel and function during the day. Regularly needing an alarm to drag yourself awake, relying on caffeine to get through the morning, or falling asleep when you sit still suggests you may not be getting enough sleep, or that something is affecting its quality.
Persistent daytime sleepiness despite enough time in bed is worth discussing with a GP, because it can be a sign of a sleep disorder such as sleep apnoea. [14]
Sleep, the brain and the body
Memory, learning and attention
Sleep plays an important role in memory. Research suggests that during sleep, newly learned information is replayed and reorganised, strengthening some memories and integrating them with existing knowledge. Both slow-wave sleep and REM sleep appear to contribute, in different ways. [15]
Lack of sleep affects attention quickly. In a well-known laboratory study, 48 healthy adults were restricted to four, six or eight hours in bed a night for two weeks. Those with four or six hours developed cognitive deficits equivalent to up to two nights without any sleep, yet their sleepiness ratings suggested they were largely unaware of how impaired they had become. [16] This gap between how impaired someone is and how impaired they feel is one reason chronic short sleep is easy to underestimate.
Emotional regulation
Sleep and mood are closely linked. Experimental studies show that sleep loss heightens emotional reactivity to negative experiences and weakens the brain's ability to regulate it, and REM sleep is thought to help process emotional memories. [17] The relationship works both ways: anxiety and low mood can disrupt sleep, and poor sleep can worsen both.
Does sleep clear waste from the brain?
You may have read that sleep "cleans" the brain. This idea comes largely from a 2013 study in mice, which found that the space between brain cells increased by around 60% during sleep and that beta-amyloid, a protein linked to Alzheimer's disease, was cleared more quickly. [18]
The picture has since become more complicated. A 2024 mouse study using different methods found that clearance was reduced, rather than increased, during sleep and anaesthesia, a finding that other researchers have disputed. [19] In humans, a small study of patients undergoing tests for suspected fluid disorders found that one night of sleep deprivation slowed the clearance of a tracer substance from the brain. [20] Brain waste clearance during sleep is therefore an active and promising area of research, but it should not be presented as an established human fact, and claims that sleep habits prevent dementia go beyond the current evidence.
Physical recovery and muscle
The most reproducible pulse of growth hormone occurs shortly after falling asleep, during deep slow-wave sleep. [21] In a small experiment with 13 young adults, one night without sleep reduced muscle protein synthesis by 18% compared with a normal night. [22] A small study of 11 college basketball players, without a control group, found that extending sleep over several weeks was followed by faster sprint times and better free-throw accuracy. [23]
These studies are small and do not show that more sleep always means more muscle or faster recovery. They do support the practical point that consistently short sleep is a poor foundation for training and recovery.
Immune function
Sleep and the immune system interact closely. In a study of 164 healthy volunteers deliberately exposed to a cold virus, people who habitually slept less than six hours were more likely to develop a cold than those who slept more than seven. [24] A 2023 meta-analysis found that objectively measured short sleep around the time of vaccination was associated with a weaker antibody response, although self-reported short sleep was not clearly linked and the studies were small. [25]
Metabolic health
Sleep affects how the body handles energy. In a landmark laboratory study of 11 healthy young men, it took about 40% longer than normal for their blood sugar to return to normal after a high-carbohydrate meal when they were in a state of sleep debt. [26] A small study of 12 men found that two nights of short sleep lowered leptin, a hormone that signals fullness, raised ghrelin, which stimulates appetite, and increased hunger. [27] A meta-analysis of experimental studies found that partial sleep deprivation led people to eat around 385 more calories a day on average, with no significant change in energy expenditure. [28] In a randomised trial of 80 adults with overweight who habitually slept less than 6.5 hours, extending sleep by about 1.2 hours a night reduced daily energy intake by around 270 calories compared with a control group over two weeks. [29]
A meta-analysis of prospective studies involving more than 1.3 million people found that both short and long sleep were associated with a higher risk of death. [30] These are associations. Long sleep in particular may reflect existing illness rather than cause it. The American Heart Association now includes sleep duration among its eight core measures of cardiovascular health. [31]
Sleep, stress and cortisol
Stress and sleep influence each other. Psychological stress activates the body's stress response, including the hypothalamic-pituitary-adrenal (HPA) axis, which regulates cortisol. Heightened arousal at night makes it harder to fall and stay asleep, and sleep deprivation in turn appears to raise evening cortisol levels. Researchers describe the relationship as complex and two-way. [8]
It is common to see poor sleep blamed on "high cortisol" and products marketed to lower it. Cortisol normally rises sharply after waking, and expert guidelines stress that measuring this rise accurately depends on strictly timed sampling. [9] A single measurement therefore says little on its own, and cortisol is only one part of a much wider system. Approaches with better evidence for stress-related sleep problems include regular routines, physical activity, time to unwind before bed, addressing sources of worry during the day, and, for persistent insomnia, CBT-I. [32]
Sleep and skin health
Sleep and skin are often linked in marketing, sometimes with claims that go well beyond the evidence. The research falls into several types, and it helps to keep them separate.
How tiredness shows on the face
Controlled studies show that people notice sleep loss in a face. In one study, photographs of people taken after sleep deprivation were rated as looking less healthy and more tired than photographs of the same people after normal sleep. [33] A follow-up study found that sleep-deprived faces were rated as having more hanging eyelids, redder and more swollen eyes, darker circles under the eyes, and paler skin. [34] These are short-term changes in appearance after a night without sleep. They do not show lasting skin ageing.
Skin barrier and hydration
The skin barrier keeps water in and irritants out. Its function is often measured as transepidermal water loss, the amount of water evaporating through the skin. In a study of 60 women, good sleepers had fewer signs of intrinsic skin ageing than poor sleepers, and 30% greater skin barrier recovery 72 hours after a mild injury. [35] The study was funded by a cosmetics company, all the participants were white women, and the study was observational, so it cannot show that poor sleep caused the differences. Other small studies on sleep and skin hydration exist, but the evidence remains limited.
Inflammatory skin conditions
Itchy skin conditions such as atopic eczema and psoriasis commonly disrupt sleep. Sleep disturbance affects a large proportion of adults with atopic eczema, [36] and a review of psoriasis describes sleep disorders as both a consequence and a possible contributor, creating a cycle. [37] If a skin condition is keeping you awake, effective treatment of the skin condition is usually part of improving sleep, so it is worth discussing with a GP or dermatologist.
Wound healing
In an experimental study, restricting sleep to two hours a night for three nights delayed the healing of small skin wounds by almost a day. [38] The evidence comes from small, controlled studies and does not translate into a specific effect for everyday skin.
What this means in practice
Good sleep is a sensible part of looking after your skin, alongside sun protection and a suitable skincare routine. Better sleep may help skin look less tired and support normal barrier function. The evidence does not show that improving sleep reverses wrinkles, measurably increases collagen or reverses skin ageing.
Sleep and healthy ageing
What changes with age
Sleep changes across life. A large analysis of studies in healthy people found that, across adulthood, total sleep time, deep slow-wave sleep and REM sleep tend to decrease with age, while time awake after falling asleep increases. [39] Sleep need does not simply disappear with age, and persistent poor sleep in later life is not something to accept as inevitable. It is often linked to health conditions, medicines, pain or sleep disorders that can be addressed.
Sleep duration, regularity and long-term health
Observational studies have found that people who report short or long sleep have a higher risk of death than those who sleep a moderate amount. [30] More recent research suggests that sleep regularity, meaning going to sleep and waking at similar times each day, may be at least as strongly associated with health outcomes as sleep duration. In a UK Biobank study of around 60,000 people using wrist-worn devices, people in the four more regular groups had a 20% to 48% lower risk of death than those in the least regular group. [40] Researchers have since noted that sleep regularity can be measured in different ways, which can give different results.
These studies show associations. People who sleep regularly may differ in many other ways, and the studies cannot prove that changing sleep habits will extend life.
Biological age
Researchers have explored links between sleep and markers of biological ageing, such as epigenetic clocks, which estimate age from chemical marks on DNA. One study of more than 2,000 older women found that insomnia symptoms were associated with more advanced epigenetic age. [41] A small experiment in 29 older adults found that a single night of partial sleep deprivation increased the activity of genes associated with cellular ageing. [42]
These findings are interesting, but they are early, mostly small and observational or short-term. No research shows that optimising sleep reverses biological age or directly extends lifespan. Juvenology's guide to biological age explains what these tests can and cannot tell you.
What you can reasonably act on
The strongest practical message is straightforward: getting enough sleep, on a regular schedule, is one of the foundations of good health, alongside physical activity, nutrition and social connection. Persistent sleep problems are worth addressing because they affect how you feel and function now, and because they are often treatable.
What causes poor sleep?
Poor sleep usually has more than one cause, and it is rarely a simple failure of willpower. Common contributors include:
Stress, worry and low mood. A busy or anxious mind is one of the most common reasons for difficulty falling or staying asleep. [43]
Irregular schedules. Changing bedtimes and wake times, including long lie-ins at weekends, can unsettle the body clock.
Caffeine. Caffeine can affect sleep many hours after it is consumed. In a small study of 12 healthy sleepers, 400 mg of caffeine taken six hours before bed reduced total sleep by more than an hour. [44]
Alcohol. Alcohol can make it quicker to fall asleep, but it increases disruption in the second half of the night, and at moderate to high doses it reduces REM sleep. [45]
Nicotine, which is a stimulant.
The bedroom environment, including noise, light, and a room that is too hot or too cold. [43]
Late-evening light and stimulating activities, including bright screens.
Pain, discomfort and health conditions, such as reflux, breathing problems, an overactive thyroid, needing to pass urine at night, and itchy skin conditions.
Medicines, including some antidepressants, steroids and decongestants. A pharmacist or GP can check whether a medicine might be affecting sleep. Do not stop a prescribed medicine without advice.
Caring responsibilities, including young children and caring for a relative.
Shift work, which places sleep at times when the body clock is promoting wakefulness.
Recognising what applies to you is more useful than a long list of generic rules.
Blue light, screens and sleep
What blue light is
Blue light is part of the visible light spectrum. The sun is by far the largest source. LED lighting and the screens of phones, tablets, computers and televisions also emit blue light, at much lower levels than daylight. [46]
Daytime light helps; evening light can delay sleep
Because the cells in the eye that set the body clock are especially sensitive to blue wavelengths, the timing of light exposure matters. Bright light during the day, especially outdoors in the morning, helps anchor the body clock. Bright light late in the evening can delay it and suppress melatonin. [5]
In one laboratory study, people who read on a light-emitting e-reader in the evening took longer to fall asleep, produced less melatonin, had a later body clock and felt less alert the next morning than when they read a printed book. [6] This was a small study of prolonged reading in controlled conditions, and everyday screen use may have smaller effects. What you do on a screen also matters: work emails, gaming or social media can be more stimulating than the light itself.
The NHS advises not watching television or using devices such as smartphones right before going to bed, [43] and its Every Mind Matters service suggests avoiding phones, tablets and computers for an hour before bed. [47]
Night mode
Night mode settings shift screen colours towards warmer tones. In a study of young adults, there were no significant differences in sleep between people using night mode, using their phone normally or not using it before bed. In a later analysis of people already getting about seven hours of sleep a night, not using a phone before bed was linked with slightly better sleep efficiency. [48] Lowering brightness, finishing screen use earlier and choosing calmer content are likely to matter more than colour settings alone.
Blue-light-filtering glasses
A Cochrane review found that the effects of blue-light-filtering spectacles on sleep quality were indeterminate, with inconsistent results across six small trials. It also found they may not reduce eye strain from computer use. [49] Blue-light glasses are not a proven treatment for poor sleep.
Screens and skin: different from sunlight
Claims that everyday screen use ages the skin are not supported by good evidence. Measurements show that phones, tablets and laptops emit far less blue light than sunlight, even on a cloudy day. [46] In laboratory studies, high-intensity visible light caused darker and longer-lasting pigmentation in people with darker skin, [50] and visible light can worsen melasma. Those studies used powerful lamps, not screens. For skin, daily sun protection is the priority, and tinted sunscreens containing iron oxides help block visible light for people with melasma or pigmentation concerns. [51]
Insomnia: when difficulty sleeping becomes persistent
What insomnia is
Insomnia means regularly having difficulty falling asleep, staying asleep or waking too early and not being able to get back to sleep, despite having the opportunity to sleep, and feeling tired or impaired during the day as a result. [43] The daytime effects matter: someone who sleeps six hours and feels fine does not necessarily have insomnia.
Occasional poor nights are normal, especially during stress, illness or change. Short-term insomnia often settles once the trigger passes. Insomnia that continues for three months or longer is called long-term or chronic insomnia. [43, 32]
Why insomnia can persist
Insomnia often starts with a trigger, such as stress, illness or a new baby, but continues after the trigger has gone. Lying awake for long periods, worrying about sleep, going to bed earlier to "catch up" or spending time in bed doing other things can teach the brain to associate the bed with being awake. Over time the worry about sleep can become a cause of poor sleep in its own right.
Cognitive behavioural therapy for insomnia (CBT-I)
The NHS says a GP may offer CBT, either face to face or through an online self-help programme, [43] and the European insomnia guideline recommends CBT-I as the first-line treatment for chronic insomnia. [32] It is a structured programme that usually includes:
Sleep education about how sleep works.
Stimulus control, which rebuilds the link between bed and sleep.
Sleep restriction or compression, a carefully managed technique that temporarily matches time in bed to actual sleep, then extends it. It should be guided by a trained professional or a validated programme.
Cognitive techniques that address unhelpful worries and beliefs about sleep.
Relaxation techniques.
CBT-I can be delivered face to face, in groups or through digital programmes. NICE recommends the digital CBT-I programme Sleepio for treating insomnia in primary care, for people who would otherwise be offered sleep hygiene advice or sleeping pills. [52] NICE also notes that face-to-face CBT-I is not routinely available on the NHS for most people, which is why digital options matter. [53] American guidance recommends against using sleep hygiene advice on its own as a treatment for chronic insomnia. [54]
The NHS says GPs now rarely prescribe sleeping pills for insomnia, and when they do, it is only for a few days or weeks at most, because of side effects and the risk of dependence. [43]
When to see a GP about insomnia
The NHS advises seeing a GP if changing your sleep habits has not worked, you have had trouble sleeping for months, or your insomnia is affecting your daily life in a way that makes it hard to cope. [43]
Sleep apnoea and other sleep disorders
Some sleep problems are caused by medical conditions that need diagnosis and treatment. The descriptions below are to help you recognise when to seek advice, not to diagnose yourself.
Obstructive sleep apnoea
In obstructive sleep apnoea (OSA), the airway repeatedly narrows or closes during sleep, causing breathing to pause and sleep to be disrupted, often without the person realising. NICE recommends assessing people who have two or more features such as snoring, witnessed pauses in breathing, choking during sleep, unrefreshing sleep or morning headaches. [55] In women, sleep-disordered breathing becomes more common after the menopause. [56, 57]
The NHS notes that sleep apnoea can be serious if it is not diagnosed and treated, and it is linked with high blood pressure, stroke, type 2 diabetes, heart disease and accidents caused by tiredness. [14] For moderate or severe sleep apnoea, NICE recommends a CPAP machine, which keeps the airway open during sleep, alongside lifestyle advice. [55]
Daytime sleepiness and driving
Do not drive if you feel excessively sleepy. The NHS advises that you may need to tell the DVLA if you have sleep apnoea, and that you must not drive until symptoms such as feeling very tired are under control. [14] The DVLA's guidance on excessive sleepiness explains when you must tell them. [58] If you regularly fall asleep unintentionally during the day, speak to a GP.
Restless legs syndrome
Restless legs syndrome causes an overwhelming urge to move the legs, often with uncomfortable sensations, that is worse in the evening and at rest and eases with movement. It can make falling asleep difficult. It is thought to be linked to iron levels and the brain chemical dopamine, and it can occur during pregnancy. [59]
Circadian rhythm sleep-wake disorders
In these disorders, the body clock is out of step with the desired schedule. In delayed sleep-wake phase disorder, for example, people have trouble falling asleep at the desired bedtime and cannot wake up in the morning. It is much more common in teenagers and young adults. [60] Problems caused by shift work can also fall into this group.
Narcolepsy
Narcolepsy is a rare condition that causes sleepiness and muscle weakness that cannot be controlled, including, in some people, sudden muscle weakness that can cause a fall (cataplexy). You must tell the DVLA if you drive and have narcolepsy. [61]
Other conditions
Other sleep-related conditions include sleepwalking, night terrors, nightmares, and REM sleep behaviour disorder, in which people act out their dreams. Any sleep behaviour that is dangerous, new in adulthood or worrying to a bed partner should be discussed with a GP.
Sleep in perimenopause and menopause
Why sleep can change
Sleep problems are common during perimenopause and after menopause. The NHS notes that difficulty getting to sleep or staying asleep can affect daily life, and that sleep problems may be worse with night sweats. [62] Hot flushes are a major contributor to sleep complaints during the menopausal transition. [57] Changes in hormones, mood, anxiety and life circumstances can all contribute to insomnia symptoms.
Sleep-disordered breathing also becomes more common after menopause, [56] so snoring, pauses in breathing or daytime sleepiness should not be put down to hormones without considering it. [57]
Sleep, skin and wellbeing in midlife
Perimenopause can also bring changes in skin dryness and texture, and poor sleep can affect mood, concentration and energy. Juvenology's guide to perimenopause skin changes covers the skin side in more detail.
Getting help
NICE's menopause guideline recommends considering menopause-specific cognitive behavioural therapy as an option for sleep problems associated with the menopause. [63] A GP or menopause specialist can talk through options, including hormone replacement therapy and non-hormonal approaches, based on your history. Not every midlife sleep problem is hormonal, so other causes such as stress, pain, medicines and sleep apnoea are worth considering too.
How to improve your sleep
Start with the foundations
Most practical sleep advice falls into a few categories. Some has stronger evidence than others, and what helps most depends on what is affecting your sleep.
Habit | Why it may help | Strength of evidence |
A regular wake time, every day | Anchors the body clock and builds steady sleep pressure | Strong rationale; a core part of CBT-I |
Daylight in the morning and during the day | Strengthens the body clock and supports earlier, more stable timing | Strong for circadian timing |
Regular physical activity | Small benefits for sleep time and moderate benefits for sleep quality in studies | Moderate; the NHS advises not exercising in the 4 hours before bed |
Limiting caffeine later in the day | Caffeine can reduce sleep many hours after it is taken | Good experimental evidence |
Limiting alcohol, especially near bedtime | Alcohol disrupts sleep in the second half of the night | Good experimental evidence |
A dark, quiet, comfortable, cool bedroom | Reduces disturbances | Reasonable; depends on your environment |
A wind-down period before bed | Helps the transition from activity to rest | Reasonable; individual |
Dimming lights and screens in the evening | Reduces light-related delay of the body clock | Moderate; content and timing matter too |
Avoiding large meals late in the evening | May reduce discomfort and reflux | Limited; individual |
Keeping naps short and early | Avoids reducing sleep pressure before bedtime | Reasonable; long or late naps can delay sleep |
Sources: NHS, Every Mind Matters, European insomnia guideline and studies cited in this guide. [43, 47, 32, 44, 45, 64]
Regular wake time
If you change only one thing, a consistent wake time, including at weekends, is often the most useful. It keeps the body clock steady and helps sleep pressure build at a predictable time. Going to bed when you feel sleepy, rather than at an arbitrary early time, works better than trying to force sleep.
Daylight
Getting outside in daylight in the morning, even on a cloudy day, gives the body clock a strong signal. Indoor lighting is much dimmer than daylight. Continue to use sun protection appropriate for the season and your skin.
Caffeine, alcohol and nicotine
Caffeine's effects can last into the evening. [44] The NHS advises not drinking tea or coffee, or alcohol, and not smoking in the six hours before bed. [43] Alcohol may help you fall asleep, but it disrupts sleep later in the night. [45]
Physical activity
A meta-analysis of 66 studies found that regular exercise has small benefits for total sleep time and moderate benefits for sleep quality. [64] The NHS advises exercising regularly during the day but not in the four hours before bed. [43]
Naps
A short nap early in the afternoon can help if you are sleep deprived, but long or late naps reduce sleep pressure and can make it harder to fall asleep at night. If you have insomnia, avoiding naps is usually advised. [43]
Build a realistic evening routine
The aim of an evening routine is to give your body and mind a clear signal that the day is ending. It does not need to be elaborate, and it should fit your life. An example to adapt:
When | What you might do |
Early evening | Finish heavy meals and strenuous exercise if they tend to keep you alert. Avoid caffeine. |
1–2 hours before bed | Dim the main lights. Write down any worries or tomorrow's tasks so they are out of your head. |
30–60 minutes before bed | Put work and stimulating screens aside. Choose something calming, such as reading, a bath, stretching or quiet music. |
Bedtime | Go to bed when you feel sleepy. Keep the room dark, quiet and comfortable. |
Morning | Get up at your usual time, whatever kind of night you had, and get daylight early. |
If shift work, a young baby or caring responsibilities make this impossible, focus on what you can control, such as darkness and quiet during your sleep period and a consistent routine around it.
What to do when you cannot sleep
Lying in bed trying hard to sleep usually makes sleep harder. Effort and frustration increase alertness. Approaches from CBT-I can help:
If you are still awake after around 20 minutes, get up. Sit somewhere comfortable in dim light and do something quiet and calming, then return to bed when you feel sleepy. [47] This is part of stimulus control, which helps the brain re-associate bed with sleep. [54]
Use the bed only for sleep and sex, not for working, scrolling or watching television.
Avoid clock-watching. Turn the clock away. Checking the time adds pressure.
Do not try to compensate by going to bed much earlier, lying in or napping for long periods, which can weaken sleep pressure the next night.
Accept that an occasional poor night is normal. One bad night is unpleasant but unlikely to cause lasting harm, and you will usually sleep better the following night as sleep pressure builds.
Breathing exercises and relaxation can help some people wind down, but no technique guarantees sleep. If difficulty sleeping persists for weeks or months, speak to your GP about CBT-I.
Supplements, melatonin and sleep products
Melatonin
In the UK, melatonin is available on prescription only. It is not sold as a food supplement as it is in some other countries. It is mainly prescribed for short-term sleep problems in people aged 55 and over, and specialists may prescribe it for longer-term sleep problems in some children and adults. [65] Research suggests any benefit for sleep is modest. [66] Ask a GP or pharmacist for advice rather than buying melatonin online.
Magnesium
Magnesium is widely marketed for sleep. A systematic review found only three small trials, involving 151 older adults, with low to very low quality evidence, and concluded that the research was not good enough to support recommendations. [67] People with a magnesium deficiency or a medical condition should seek advice before taking supplements.
Herbal products
A systematic review of 14 trials found no significant difference between any herbal medicine, including valerian, and placebo for insomnia, and concluded that the evidence did not support their use. [68] In the UK, some herbal sleep remedies carry a Traditional Herbal Registration, which states that the product is used based on traditional use only, not on proof that it works. [69] Herbal products can interact with other medicines, so check with a pharmacist.
Blue-light glasses
As above, evidence that blue-light-filtering glasses improve sleep is uncertain. [49]
White noise and sound machines
Steady background sound may help some people by masking disruptive noise. A systematic review found the evidence that continuous noise improves sleep was of very low quality, and some studies suggested it could worsen sleep. [70] Earplugs are a simple alternative if noise is the problem.
Weighted blankets
A Swedish trial of 120 adults with insomnia and a psychiatric condition found that nearly 60% of those using a weighted blanket had a positive response, compared with about 5% using a light blanket. The study could not be blinded, because participants knew which blanket they had been given. [71] A 2024 review found that half of the studies of weighted blankets were at high risk of bias, and the pooled result for insomnia was uncertain. [72] They are not suitable for young children or people who cannot easily remove them.
Consumer products versus medicines
Sleep products sold as wellbeing aids are not assessed in the same way as medicines. Be cautious of products that promise to cure insomnia or guarantee better sleep. If you have persistent insomnia, CBT-I has stronger evidence than any supplement.
Do sleep trackers work?
What they measure
Wearable devices and phone apps typically estimate sleep from movement and heart rate, sometimes with other signals such as skin temperature or blood oxygen. Most do not measure brain activity, which is how sleep stages are defined in a sleep laboratory. [73]
How accurate they are
A study of seven consumer devices found that they were good at detecting sleep but often missed periods of wakefulness, counting them as sleep, and their sleep stage estimates were inconsistent. [74]
What they cannot do
The American Academy of Sleep Medicine states that consumer sleep technology cannot be used to diagnose or treat sleep disorders, although it may help conversations with a clinician. [73] A tracker that reports good sleep does not rule out sleep apnoea, and a poor sleep score does not mean you have a disorder.
When tracking becomes counterproductive
For some people, chasing a perfect sleep score creates anxiety that makes sleep worse. Clinicians have described this "perfectionistic quest for the ideal sleep" as orthosomnia. [75] If tracking makes you worry about your sleep, take a break from it and focus on how you feel during the day.
A 14-day sleep plan
This plan is a way to observe your sleep and build steady habits. It is not a treatment for diagnosed insomnia or a sleep disorder, and it does not include sleep restriction, which should only be done with professional guidance.
Days 1 to 7: observe
Keep a simple sleep diary each morning:
Record | Example |
Time you went to bed | 11.15pm |
Roughly how long it took to fall asleep | 30 minutes |
Times you woke and for how long | Once, around 20 minutes |
Time you woke for the day and got up | 7am, up at 7.10am |
Caffeine and alcohol (what and when) | Coffee at 3pm; one glass of wine at 8pm |
Exercise and daylight | 20-minute walk at lunchtime |
How you felt during the day (1–5) | 3 |
During this week, make only two changes:
Fix your wake time, the same every day, including at weekends.
Get daylight within an hour or two of waking where possible.
Days 8 to 14: adjust one or two things
Look at your diary and choose one or two changes that fit what you noticed:
If you drink caffeine after lunchtime, try moving it earlier.
If screens or work run late, set a finish time and add a short wind-down.
If your bedroom is light, noisy or warm, address that.
If you lie awake for long periods, use the "get up if you cannot sleep" approach.
If alcohol features most evenings, try alcohol-free evenings and compare.
Keep everything else steady, so you can see what makes a difference.
Review
At the end of two weeks, look at how you feel during the day as well as at your sleep. Small improvements are worth continuing. If you are no better, or your sleep problems are affecting your daily life, take your diary to your GP. It will help them understand the pattern and decide whether CBT-I or further assessment is needed.
When poor sleep needs medical assessment
Speak to a GP if you have:
trouble sleeping for months, or sleep problems that make daily life hard to cope with; [43]
loud snoring with pauses in breathing, choking or gasping during sleep; [14]
excessive sleepiness during the day, or falling asleep unintentionally;
an urge to move your legs that stops you falling asleep; [59]
unusual behaviours during sleep, such as acting out dreams;
low mood, anxiety or worry that is affecting your sleep.
If you feel sleepy while driving, stop somewhere safe. Do not drive if you are excessively sleepy, and check whether you need to tell the DVLA if you are diagnosed with a condition that causes excessive sleepiness. [14, 58] If you are having thoughts of harming yourself, contact your GP urgently or call NHS 111. You can also call Samaritans free on 116 123. In an emergency, call 999.
Juvenology and healthy ageing
Juvenology Clinic is a nurse-led aesthetics, skin health and longevity clinic at 82 King Street, Maidstone, Kent. It is not a sleep clinic. It does not diagnose or treat insomnia, sleep apnoea or other sleep disorders, and these should be assessed through your GP.
Sleep is one of the areas covered in the clinic's longevity medicine memberships. Marina Kostadinova-Yankova, the clinic's founder, reviews sleep alongside health history, diet, stress and test results, and includes it in a written plan covering nutrition, movement, sleep and stress. She writes to your GP if anything needs medical attention. [76] The clinic also offers HeartMath heart rate variability coherence training as a stress-management practice. It is not a treatment for insomnia or for anxiety or other mental health conditions. [77]
For visible skin concerns, the clinic's general in-person consultation is 30 minutes and costs £50.
If you are interested in the clinic's longevity or skin services, you can arrange a free discovery call by WhatsApp to discuss which service may suit you. A discovery call is not a clinical sleep assessment.
Frequently asked questions
How many hours of sleep do adults need?
Expert panels recommend that adults regularly sleep for seven hours or more a night, with seven to nine hours a common recommended range. [12, 13] Individual need varies, so how you feel during the day is the best guide.
Is eight hours necessary for everyone?
No. Eight hours is a popular round number, not a universal requirement. Some people feel well on seven hours and others need nine. Consistently feeling refreshed and alert matters more than hitting a particular figure.
Why am I tired after eight hours in bed?
Time in bed is not the same as sleep. You may be taking a long time to fall asleep or waking often. Poor sleep quality, an irregular schedule, alcohol, depression, some medicines and sleep disorders such as sleep apnoea can all leave you tired despite enough time in bed. If daytime tiredness persists, speak to a GP. [14]
Is deep sleep more important than REM sleep?
Both matter, and they do different things. Deep sleep is associated with physical recovery and relief of sleep pressure, and REM sleep with emotional processing and some types of memory. [1, 15] Trying to maximise one stage, for example based on a tracker's estimate, is not a useful goal.
Can you recover lost sleep?
Partly. After a short period of poor sleep, you tend to sleep longer and more deeply to recover. But regularly cutting sleep during the week and catching up at weekends does not fully reverse the effects. In one experiment, weekend recovery sleep did not prevent metabolic changes caused by repeated sleep restriction. [78]
Does sleeping before midnight matter?
There is nothing special about midnight itself. What matters more is that your sleep is regular and aligned with your body clock, and that you get enough of it. Because deep sleep is concentrated earlier in the night, a very late and irregular schedule can still reduce sleep quality. [1, 40]
Is waking during the night normal?
Yes. Brief awakenings between sleep cycles are normal, and many are not remembered. Waking and getting back to sleep fairly quickly is not usually a problem. Regularly lying awake for long periods, especially if it affects your day, is worth addressing. [1]
How can I fall asleep more consistently?
Keep a regular wake time, get daylight in the morning, limit caffeine later in the day, give yourself time to wind down, and go to bed when you feel sleepy. If you are still awake after around 20 minutes, get up and do something calming rather than lying in bed trying. [43, 47]
Does magnesium improve sleep?
The evidence is weak. A systematic review found only three small trials in older adults, with low to very low quality evidence. [67]
Do blue-light glasses work?
There is no reliable evidence that blue-light-filtering glasses improve sleep. A Cochrane review found their effects on sleep quality were indeterminate. [49]
Can alcohol help you sleep?
Alcohol can help some people fall asleep faster, but it disrupts sleep in the second half of the night and, at moderate to high doses, reduces REM sleep. [45] It is not a safe or effective sleep aid.
Does sleep quality decline with age?
On average, total sleep time and deep sleep decrease across adulthood, and time spent awake during the night increases. [39] Significant sleep problems are not an inevitable part of ageing, however, and they are often linked to treatable health conditions, medicines or sleep disorders.
Can menopause affect sleep?
Yes. Night sweats, hot flushes and hormonal changes can disrupt sleep, and sleep-disordered breathing becomes more common after menopause. [62, 57, 56] A GP or menopause specialist can discuss treatment options.
Does poor sleep age your skin?
Short-term sleep loss can make skin look tired, with puffier eyes and darker circles, and a small study linked poor sleep quality with slower skin barrier recovery. [34, 35] There is no good evidence that poor sleep alone causes lasting skin ageing, or that better sleep reverses it.
Can improving sleep slow biological ageing?
Some studies link poor sleep with markers of faster biological ageing, but they are small and mostly observational. [41] There is no evidence that optimising sleep reverses biological age. Sleeping well is a sensible part of a healthy lifestyle for its own sake.
When should I speak to my GP?
Speak to a GP if sleep problems last for months or affect your daily life, if you snore loudly with pauses in breathing or gasping, if you are very sleepy during the day or fall asleep unintentionally, or if low mood or anxiety are affecting your sleep. [43, 14]
About Juvenology Clinic
Juvenology Clinic is a nurse-led aesthetics, skin health and longevity clinic at 82 King Street, Maidstone, Kent ME14 1BH. It was founded by Marina Kostadinova-Yankova, an NMC-registered nurse with more than 25 years of nursing experience. She leads the clinic's longevity medicine service. Read more about Marina and the clinic.
This guide is general educational information and does not diagnose or treat sleep disorders. If you have persistent sleep problems or any of the symptoms described in this guide, speak to your GP. Information was checked in October 2026.
References
Bonnet MH, Arand DL. EEG arousal norms by age. J Clin Sleep Med. 2007;3(3):271–274.
Rasch B, Born J. About sleep's role in memory. Physiol Rev. 2013;93(2):681–766.
NHS Every Mind Matters. How to fall asleep faster and sleep better.
American Academy of Dermatology Association. Melasma: self-care. Last updated 12 September 2023.
National Institute for Health and Care Excellence. HTG624: the technology.
NHS. Restless legs syndrome. Last reviewed 22 September 2025.
American Academy of Sleep Medicine, Sleep Education. Delayed sleep-wake phase. Reviewed October 2020.
Juvenology Clinic. Longevity medicine. Accessed 20 October 2026.
Juvenology Clinic. HeartMath practitioner. Accessed 20 October 2026.