Why do human beings sleep? What a silly question; surely we sleep in order to rest the body and mind. Well, maybe. However, research studies have shown that simply sitting down and putting your feet up will rest the human mind and body quite effectively. There must be more to sleep than resting. So why do we go to a special place and make ourselves unconscious for several hours every night? There are a couple of theories about the function of sleep in humans. One theory is that sleep is a throwback evolutionary adaptation, which aided the survival of the human species. Sleep enabled our ancestors to preserve energy when food supplies were scarce. You burn fewer calories when you’re asleep, therefore you don’t need to eat so much. And you never know when the next ox or deer is going to wander by. Sleep as a mean of preserving energy would have served a useful purpose for our cave dwelling ancestors, but isn’t it a little unnecessary in our 24-hour convenience store society? There must be more to sleep than energy preservation, too.
A competing theory of the function of sleep is ‘Restoration Theory’ and here we can see the links to physical and mental health. In a single night, a person goes through several cycles of sleep, each with a number of stages. Over the course of these stages, sleep becomes deeper, eventually reaching the stage of sleep known as REM sleep (Rapid Eye Movement), and then the cycle starts again. Each of these stages is equally important, but Stage 4 sleep is particularly significant. This is the deepest stage of sleep. During this stage, the body releases growth hormone to help repair any damage, internal and external, and the proteins that supply the immune system are replenished during. Chemicals in the brain (neurotransmitters) are also topped up during this deepest sleep, as their levels deplete over the course of the day. There is some evidence to suggest that imbalance of key neurotransmitters such as Serotonin and Dopamine are a factor in depression. When you add in the fact that our mental health suffers when our physical health is not at its best, it isn’t difficult to see why sleep is so vital to mind and body. Without deep sleep, mind and body do not have adequate opportunity to restore. Good sleep is a bit like hitting the reset button every night.
But what if you have trouble sleeping? According to NHS research, a third of the population in the UK has problems with sleeping. Insomnia is characterised by a difficulty falling asleep (i.e. it takes more than thirty minutes), combined with frequent episodes of wakefulness during the night. In the course of the stages of sleep, we inevitably enter a shallow phase of sleep several times in a night. This will make a person momentarily more aware but, more often that not, sleep returns quite quickly. But for some, that momentary wakefulness seems to trip a switch and they just know that sleep is not going to return. Insomnia is a huge public health problem. People who experience it describe it as like being caught in a vicious cycle of poor sleep, followed by anxiety about poor sleep, which inevitably leads to further poor sleep. Insomnia effects concentration levels, increases feelings of irritability and can effect blood sugar levels, leading to greater consumption of sugary foods. This sounds like a recipe for stress, inter-personal difficulties and weight gain.
Thankfully, there are some simple steps that can be taken to improve the quality of sleep.
· Reduce or, preferably, eliminate caffeine intake in the couple of hours before bedtime. Even tea contains levels of caffeine that can impair sleep. If insomnia is a real problem, it might be worth changing to herbal or fruit teas in the evening.
· Avoid alcohol in the couple of hours before going to bed. Although alcohol has a relaxant effect when first consumed, it will act as a stimulant later on.
· Try taking some exercise in the day, as this will help the body expend excess energy. However, exercise releases adrenaline, so it is best to avoid doing exercise in the couple of hours before going to bed.
· Aim for a regular bedtime. Some specialists advise ‘sleep restriction’ if the insomnia is chronic and having a detrimental effect on your daily life. This means delaying by an hour or so the time that you would normally go to bed. This seems counter-intuitive, but there is sense in it. There are few things more frustrating than lying in bed, wide-awake and unable to get to sleep. Better to delay it for a short while until you are really tired and ready for sleep.
· Get rid of distractions from the bedroom, including TVs, computers, games consoles and mobile devices. Many people are now so addicted to their devices that they keep them by their side in the bedroom. Worse still, they actually check them if an alert comes through, regardless of the time of night. This is a problem unique to this era. I frequently hear the excuse, “I can’t leave my phone downstairs. I use it as my alarm clock!” When you consider that a decent alarm clock costs about a fiver, this seems a small price to pay for better quality sleep. There is now widespread agreement that the ‘Blue Light’ generated by screens will have a negative impact on quality of sleep, as it mimics daylight. If your brain detects daylight, it will begin the process that leads to wakefulness. This will eventually disrupt your body clocks natural circadian rhythms, which can have devastating consequences for health. Better to treat the bedroom as a sacred space.
· Try a relaxation exercise before going to bed. Body scans (tensing and relaxing different parts of the body in turn), breathing exercises, guided imagery or listening to a restful sound can all help. There are countless apps to help with this now.
There is no hard and fast rule about the amount of sleep a person needs. This could be anywhere within the range of five to eleven hours, depending on age. Adolescents need more sleep (yes, it’s a biological fact!), and sleep needs will decline over the lifespan. This is thought to be linked to changes in the level of melatonin in the brain as we age. Equally, some people are night owls and others are morning larks. It is important to go with your body clock rather than fight against it. Although your body clock can be retrained where necessary (e.g. if you work shifts), this is often at the expense of side effects elsewhere.
The link between sleep and mental health is well documented. Having things ‘on your mind’ can be a major barrier to good quality sleep. Equally, not getting a good night’s sleep can make those ‘things’ harder to cope with. So there is a bit of a chicken and egg conundrum here; does poor sleep lead to mental health problems, or do mental health problems lead to poor sleep? The jury is still out. However, there can be little doubt that making attempts to address one will benefit the other.
As it's National Sleep Week, it seems a good time to share some resources from Sleep Help, including some useful guidance for improving sleep if you also live with autism.