It’s no wonder so many of us have trouble sleeping. The stressful commute, bright lights outside, or the noisy neighbours – our city lifestyles don’t make it easy. Then we add in our own bad habits, caffeine, and the late-night ‘ping’ from our smartphones. 

This is just modern life, right? The trouble is, being tired for a few days is only part of the story. Most of us don’t know that a lack of sleep has a big impact on the rest of our lives. Poor sleep means we’re at more risk of diabetes, obesity and heart disease – and it plays havoc with our mental health. 

Good sleep means working in harmony with our natural circadian rhythm. This is the internal body-clock that drives sleepiness and wakefulness. It makes us sleep soundly in the early hours, then become more alert mid-morning. Darkness and daylight help make it work. 

In this article we find out more, and explore why sleeping is essential for a long and healthy life.

When you don’t sleep well

The odd night without much sleep means you’re irritable the next day. It won’t hurt your health. But after a few nights, the effects become serious. You’ll find it hard to make decisions, and you’ll feel low and sluggish. That’s because you’re not re-setting your body and brain each day, as nature intended.

Sleep protects your mental health

The science tells us that chronic sleep problems can lead to long-term mood disorders like depression and anxiety. One study shared by the NHS followed the sleeping habits of people with mental health problems. Most of them regularly slept for less than six hours a night, and that’s not enough. The hours you sleep are not like a bank account. You can’t go overdrawn for a few months and pay back the debt next year.

Sleeping helps you stay lean

There’s also lots of evidence that good sleep habits help you manage your weight. It looks as if there are two reasons for this. Firstly, sleep-deprived people have less leptin, the hormone that makes you feel full. Second, they have more ghrelin, the hormone that makes you want to raid the fridge. 

This is a double-whammy that no-one wants. It makes it harder for you to control your impulses and cravings. That means you’ll find yourself both looking for high-calorie foods and feeling less satisfied afterwards. So if you want a lean body, sorting out your sleeping habits should be high on your list.

You need sleep for physical recovery

There are two main phases in a healthy night’s sleep. The first one regenerates and heals your body after the trials of the day – it’s called Slow Wave Sleep or SWS. If you’ve been training hard or just running for the bus, this is when your muscles are repaired. Your body releases growth hormones to keep them in good nick. So sleep makes your physical recovery faster and more complete.

Sleeping keeps your brain sharp

Everyone needs a rest after a day absorbing stuff – from the news and office gossip to your kids’ school reports. In the other phase of sleep (REM), we sort out and reset the activity that’s built up in our brain while we’ve been awake. Without the full forty winks, our neurons get muddled with electrical activity. This gets in the way of new memories being laid down. 

Good sleep is needed before learning, to get your brain ready for new memories. It’s also needed afterwards, to fix those memories and prevent you forgetting. If you don’t sleep the very first night after learning something, it may never come back. That’s not good, because memories help us adapt to the world around us. 

We also know that good REM sleep fuels creativity. That doesn’t mean you’ll master the piano or cake decoration overnight (although it would help). It’s more to do with the everyday creativity that helps us think clearly and solve problems. And we all face tricky challenges every day, making decisions about our health, careers, families and relationships.

Sleep fights off lifestyle diseases

By now, you won’t be surprised to hear that bad sleep also fuels the lifestyle diseases that strain our communities and health services. Those who usually sleep less than five hours a night increase their risk of diabetes. Sleep deprivation is also linked with increased heart rate and higher blood pressure, putting extra strain on your heart. Finally, prolonged lack of sleep can disrupt your immune system, so you’re less able to fend off bugs.

Bad sleep plays havoc with the chemical substances and vital processes that occur inside your body. Consistent lack of sleep drives an increase in cortisol, a hormone whose release is associated with stress. It also means higher levels of blood sugar and premature ageing. That’s right – ‘beauty sleep’ is a real thing, and researchers have shown that just a little sleep-deprivation makes people less attractive to others.