How to get the perfect night's sleep

Diabetes, heart failure and obesity are just a few of the health conditions linked to a lack of sleep – we need it, even if science can’t yet tell us why.

The current consensus is that sleep performs two vital functions: your brain needs to flush out the metabolic by-products that have built up during the day, and the mind needs to start preparing for the day ahead by ditching any newly formed memories that are no longer needed.

Dreams are believed to be a side effect of this process, which is characterised by eye movement, hence the term Rapid Eye Movement (REM) sleep. Ensuring you get enough of both phases is crucial for getting a perfect night’s rest.

Your body has two systems that govern sleep. The first is a sleep homeostat – essentially a gauge that rises as you stay awake and drops while you sleep. Counter-balancing this is the circadian system, which provides an ‘alerting signal’ that oscillates between wakefulness and tiredness, regardless of how long you’ve been awake.

But this alerting signal can keep us awake late at night, and it can even delay the restorative, deep portion of sleep. It can also be influenced by differences in the intensity of light, so with a bit of DIY work, you can attempt to mould this cycle around the pattern of your day.

“Any light suppresses the hormone melatonin, which peaks during the night to make you feel sleepy,” says Dr Simon Archer, a chronobiologist at Surrey Sleep Research Centre. “But it’s actually blue-light receptors in the eye that are responsible for doing that, so light enriched with red will help you fall asleep faster, whereas light enriched with blue will coax you into wakefulness in the morning.” So the ideal bedroom would make use of lights infused with red to wind your circadian system down during the evening, and a blue light that gradually gets brighter to kick start it again in the morning. Time to stock up on those coloured bulbs.

Read more about sleep:

• Michael Mosley: How much sleep do you really need?
• What is your brain doing while you sleep? – Dr Guy Leschziner
• Wake therapy: the new technique that starves people of sleep to treat depression

Without the full eight hours, your sleep homeostat won’t empty entirely. Sleep researchers describe this as a ‘sleep debt’, which is measurable in scans of the brain’s electrical activity.

The ability to manage your sleep debt is partly determined by genetics: about 10 per cent of the population carry a particular combination (one from each parent) of variants of the Period 3 gene, causing them to feel tired earlier in the day so they go to bed and wake up much earlier.

It’s also important to identify how your body reacts to a lack of sleep, and pay back your sleep debt when the opportunity arises. For some this may mean short naps in the day, others can just wait for the weekend.

The transition from sleep time to wakefulness is physiologically very stressful on the body, so you’re never going to be all that perky first thing in the morning. To get out of bed at your freshest, waking up seven to eight hours after falling asleep is ideal. Any less or any more and you risk interrupting either stage of sleep. Leaving your blinds or curtains slightly open will also help suppress melatonin production, helping you to resist 10-minute snoozes.

A tipple before bed may help you get all eight hours, but it also disrupts the initial deep stage of sleep, when the brain is revitalising itself. It’s one of the reasons you can feel drained after a boozy night out.