Sleep is now a consumer category. There are rings that score it, mattresses engineered for it, supplements marketed at it and a genre of bestselling books explaining its importance. Some of that reflects real science. A great deal of it has outrun the evidence, and the gap between the two is worth knowing about, because sleep advice has a specific failure mode: anxiety about sleep is itself one of the most reliable causes of insomnia.
The eight hour number is an average, not a target
Adults need somewhere between seven and nine hours, and where any individual sits in that range is largely genetic. Some people function well on six and a half; a smaller number need close to ten. The useful question is not how many hours you slept but whether you are sleepy during the day. Persistent daytime sleepiness indicates insufficient or poor quality sleep. Hitting seven hours and feeling fine is fine, regardless of what a device says.
The clinical summary published by the NHS on sleep and mental wellbeing is deliberately modest about hour targets for this reason, and its emphasis on routine over duration reflects where the evidence is strongest.
What reliably helps
A consistent wake time, including at weekends, is the most robust single intervention. The circadian system is entrained mainly by light and by regular timing, and a fixed wake time stabilises it far more effectively than a fixed bedtime, because you can control when you get up and cannot control when you fall asleep.
Morning light exposure is second. Ten to thirty minutes of outdoor light shortly after waking, even on an overcast British morning, delivers an order of magnitude more illuminance than indoor lighting and advances the body clock. Evening light does the opposite, which is the real mechanism behind screen advice: the issue is total light exposure and engagement, not blue wavelengths specifically.
Third, caffeine timing. Caffeine has a half-life of roughly five hours and a quarter-life of ten, meaning a 4pm coffee leaves a measurable dose in the system at midnight. People who insist caffeine does not affect their sleep are frequently right about falling asleep and wrong about sleep depth.
Fourth, alcohol. It reduces sleep latency and degrades sleep architecture, suppressing REM early in the night and producing fragmented sleep later. This is one of the least disputed findings in the field and one of the most widely ignored. Guidance from Drinkaware covers the mechanism in detail.
The treatment that actually works for insomnia
For chronic insomnia, the first-line recommended treatment in the UK is not medication. It is cognitive behavioural therapy for insomnia, a structured programme involving sleep restriction, stimulus control and cognitive work on sleep-related anxiety. NICE guidance on sleep disorders positions it ahead of hypnotic drugs, which are recommended only for short-term use because of tolerance and dependence.
Digital versions of the programme are available on prescription in parts of the UK and privately elsewhere. Its central technique is counter-intuitive: spending less time in bed, temporarily, to consolidate sleep and rebuild the association between bed and sleeping. It works better than anything sold as a sleep aid.
Where the industry oversells
Consumer trackers estimate sleep stages from movement and heart rate variability and are only loosely accurate against polysomnography. They are reasonable at total duration and poor at staging. More importantly, a documented phenomenon sometimes called orthosomnia describes people whose sleep worsens because they are anxious about their sleep scores. If a tracker makes you worry, it is making things worse.
Melatonin is a prescription medicine in the UK, licensed mainly for specific indications and jet lag rather than as a general sedative, and the doses sold over the counter abroad are typically far higher than the small physiological dose that shifts circadian timing. Most other supplements marketed for sleep have thin or no evidence.
When to seek help
Loud snoring with pauses in breathing and daytime sleepiness suggests sleep apnoea, which is common, underdiagnosed, and treatable, and it warrants a GP appointment rather than a lifestyle adjustment. Persistent insomnia lasting more than three months, or sleep problems accompanied by low mood, also deserve clinical attention rather than another product.
The short version of the evidence is unglamorous. Fixed wake time, morning light, no late caffeine, less alcohol, a dark cool room, and a willingness to get out of bed when you cannot sleep. That list has better support behind it than everything on the shelf.
Related: the UK physical activity guidelines, cutting a household energy bill, and more lifestyle coverage.
