A good night’s sleep brings more benefits than just the satisfaction of having slept well. It improves the memory, makes it easier to think clearly and make decisions, and reduces the risk of infections, diabetes, heart disease, exhaustion and other conditions.
Different people need different amounts of sleep. On average, adults need around seven hours of sleep each night. Babies need much more sleep, whereas it’s not uncommon for people to get by on five or six hours of sleep as they get older.
One common misconception is that we lie still when we sleep. That’s simply not true. In fact, we change position around five to ten times an hour. The reason for this is that the body needs to increase the flow of blood to those parts of the body which are under pressure when we lie still in one position.
Many people who have difficulties sleeping feel that they have hardly slept a wink during the night. In actual fact, that tends not to be the case. This is because you need to sleep for at least 20 minutes for the brain to actually register that you have slept.
Similarly, you need to be awake for more than five minutes in order to be aware that you have been awake during the night.
Losing essential hours of sleep harms the body. Our immune defences suffer, and we find it hard to concentrate. If you have missed out on part of your night’s sleep, Torbjörn Åkerstedt, sleep researcher and professor at Sweden’s Karolinska Institutet, recommends that you make up for this by taking a nap during the day. You only need a ten minute nap in order to feel the benefit.
Sleep is made up of cycles. Each cycle includes a number of phases, including deep sleep, which is when recovery takes place, and REM sleep, which is when you dream. In the early stages of sleep, the periods of deep sleep are longer. However, towards the end of the night we sleep less deeply and dream more. Human beings are so cleverly designed that our bodies are aware of our sleeping needs and adapt our sleep accordingly. If you sleep less one night, you will have longer periods of deep sleep the next night. Sleeping for longer is not recommended, since the crucial periods of deep sleep occur during the initial stages of sleep.