How much do you need?
For adults, guidance converges on 7 to 9 hours a night, with genuine individual variation. The useful measure is not the number but how the day goes: waking rested and not fighting sleepiness outside the early-afternoon dip means your sleep is probably adequate. Teenagers need 8 to 10 hours, and their body clock naturally pushes them later — which is why early school starts hit them hardest.
Why it matters
Chronic short sleep is not simply tiredness: it is associated with higher risk of cardiovascular disease, type 2 diabetes, weight gain, infection, road accidents and mood disorders. Memory is consolidated during deep sleep, which is why a shortened night before an exam is almost always a poor trade.
What actually works
- Consistent times, weekends included — the most effective and most neglected measure. Shifting your wake time by three hours on Saturday produces the equivalent of jet lag.
- Morning light: fifteen minutes outside after waking resets the body clock better than any supplement.
- A cool, dark, quiet room, around 18–19°C.
- No screens in the hour before bed — less for the blue light, whose effect is modest, than for stimulating content and the time it steals.
- Caffeine before early afternoon: with a half-life of five to six hours, a 5pm coffee is still working at midnight.
- No alcohol in the evening: it speeds up falling asleep but fragments the second half of the night and suppresses deep sleep.
- Don't lie awake more than twenty minutes: get up, do something calm in low light, return when sleepy.
Insomnia: when to seek help
Difficulty sleeping three nights a week for more than three months, with daytime impact, defines chronic insomnia. The first-line treatment is not medication but cognitive behavioural therapy for insomnia (CBT-I), whose long-term results clearly beat sleeping tablets. Digital CBT-I programmes are recommended in national clinical guidance in a growing number of countries and are increasingly available through primary care. Benzodiazepines and "z-drugs" carry tolerance, dependence and fall risks and have a place only for short periods.
Snoring and sleep apnoea
Loud snoring, breathing pauses noticed by a partner, gasping awakenings, morning headaches and marked daytime sleepiness suggest obstructive sleep apnoea. It is common, underdiagnosed, significantly raises cardiovascular risk, and is treatable. A sleep study — often now done at home — makes the diagnosis.