Sleep, and How It Actually Works

Sleep advice is full of confident claims, and many of them go further than the evidence allows. In this video, I'll explain how a night's sleep actually works, what the research supports, and what can help if you're sleeping badly. Through the night, you move in cycles through light sleep, deep sleep and dreaming sleep. Most deep sleep comes early in the night, while most dreaming sleep comes towards the morning. So a late bedtime costs you deep sleep, and cutting the morning short costs you dreaming sleep. Each stage of sleep seems to have a different job to do. Light sleep takes up most of the night and helps the brain to lay down memories. Deep sleep is the hardest stage to wake from and shortens with age, while in dreaming sleep the brain is nearly as active as in the day. When you fall asleep in the first place depends on two separate systems working together. Sleep pressure builds with every hour you're awake, while your body clock runs on its own daily rhythm. That's why a nap late in the afternoon can make it harder to fall asleep later on. Your body clock is set mainly by light, so as it fades in the evening, your body releases melatonin, the hormone that signals night-time. The overall brightness in the hour before bed seems to matter more than screens alone, and bright morning light keeps your clock steady. Melatonin is also made as a medicine, but in the UK it's prescription-only, licensed mainly for short-term use in people aged 55 and over. Melatonin bought online from abroad isn't regulated in the same way, so the amount it contains may not match the label. As for how much sleep you need, the NHS suggests most adults need between seven and nine hours. Regularly sleeping much longer is linked with poorer health, but that's most likely because illness causes it. So if you start needing far more sleep than usual, please get it checked. Insomnia makes that harder, and it's very common, especially around the menopause. The first recommended treatment isn't a tablet, but a form of cognitive behavioural therapy designed specifically for sleep. It may not add many hours, but it usually improves how well you sleep, and how much poor sleep takes over your life. This kind of therapy also works for people having cancer treatment, and a free six-week online version is available in some parts of the UK. One bad night won't damage your health, although your concentration will suffer the next day, so take extra care when driving. Some sleep problems have a physical cause, such as sleep apnoea, where the airway closes repeatedly and interrupts your breathing. The signs include loud snoring, pauses in breathing that a partner may notice and heavy tiredness during the day. It's worth getting checked, as treatment is available on the NHS. Everyday habits matter too, and even a large glass of wine is enough to disrupt your dreaming sleep; delaying it and shortening it through the night. Exercise in the evening is usually fine, as long as you finish a couple of hours before bedtime. Caffeine is another habit worth looking at, because it stays in your system longer than most people realise. A regular mug of coffee may need to be drunk around nine hours before bed to avoid disturbing your sleep. If you sleep badly, try moving your last coffee earlier. Working patterns affect sleep as well, and many women who work night shifts wonder whether it affects their risk of breast cancer. Night shift work is classed as probably cancer-causing, mainly because of laboratory research, but the evidence is mixed. The largest UK studies, following women for many years, found no increase in risk. If you're having cancer treatment, sleep problems are common, often because of night sweats, worry or the treatment itself. Non-drug approaches for sleep should come first, and sleeping tablets are generally only for short-term use. If poor sleep is affecting you, please get in touch with me, or my team.