Our sleep is programmed
First published in: Tages-Anzeiger – Monday, 19 June 2017
People who miss out on sleep get less out of life. Our body clock calls the shots – it’s genetically programmed and has a profound impact on our life.
People often dismiss their difficulties in getting up in the morning by claiming they are ‘night owls’. For many years, sleep researchers used that term to refer to people whose body clock predisposes them to burn the midnight oil. By contrast, ‘morning larks’ leap out of bed, eager to get going. As it turns out, the line between those two is somewhat blurred: around half of the people do not fall clearly into either of those categories, and their sleep-wake cycle lies somewhere between that of the morning larks and the night owls.
Our preferred sleep pattern is programmed by nature. The time when we get up or go to bed isn’t determined by our alarm clock alone. Deep inside, we all have a body clock (also known as our biological or circadian clock) ticking away. For the majority of people, it runs for an average of ten minutes longer than 24 hours, while in a quarter of people it runs a little shorter. Our body clock determines whether we belong to the ‘chronotype’ of early birds or to the 32 per cent of late risers. The difference is part of our genetic make-up and is hard-wired into us. It can’t simply be reprogrammed. A night owl will never become a morning lark, and vice-versa.
Melatonin regulates our sleep-wake cycle
Our sleep is also affected by environmental factors, such as the amount of artificial light we’re exposed to. When rays of light hit the retina of our eyes, signals are sent to a specific region of the brain – the suprachiasmatic nucleus. Our ‘master clock’ is ticking away right there, in that bundle of neurons above the optic nerve. It controls the release of the sleep hormone melatonin, which regulates our personal sleep-wake cycle. The hormone is released when it is dark, which is why we get tired in the evening. Bright light suppresses the production of melatonin.
The amount of sleep we need differs greatly from person to person. Voltaire and Margaret Thatcher are said to have survived on just four hours of sleep each night. Benjamin Franklin, one of the Founding Fathers of the United States and inventor of the lightning conductor, allegedly made do with only three hours’ sleep a night. By contrast, Johann Wolfgang von Goethe was a big sleeper, sleeping for ten hours a day. The same was reportedly true of Albert Einstein. The legendary automobile pioneer, Henry Ford, on the other hand, was a staunch opponent of sleeping, and even went as far as describing it as ‘entirely superfluous’.
A waste of time? On the contrary!
Is there any truth in the notion that sleep is a waste of time? Those who shun sleep like Ford like to point out that, statistically speaking, adults spend a third of their lives sleeping, in a state that is ‘unproductive’. Yet sleep is clearly essential for our regeneration. During the night, the body repairs damaged cells and forms new ones. Our muscles relax and our brain does its housekeeping: it processes our experiences, sorts out the important information from the unimportant and consolidates what we’ve learnt.
Sleep your way to fitness!
‘Beauty sleep’ isn’t a myth either. People who get a good night’s sleep are more energetic, more refreshed and healthier. Sleep deprivation can make us ill, overweight and mentally sluggish. It’s no wonder that sleep psychologists and other sleep experts have done intensive research into the optimal amount of sleep. An average of seven to eight hours has been found to be most effective. The Swiss get an enviable amount of sleep – a survey conducted in Zurich and Basel found that people in Switzerland manage around eight hours’ sleep a night on average. The amount of sleep each of us needs also has much to do with age. Over a lifetime, our sleep requirements change. Babies need a lot of sleep. Children require around ten to twelve hours of sleep in order to be able to concentrate during the day. It isn’t until after puberty that we find the amount of sleep we personally need.
There’s an easy way to check whether you’re getting enough sleep. Do you wake without an alarm clock, feeling refreshed? If you’re getting the optimal amount of sleep, you should be able to perform at a high level during the day, without feeling tired. We can make up for a temporary lack of sleep by having a sleep-in, but it isn’t possible to ‘bank’ sleep in advance.
A siesta or nap
Daniel Brunner, a specialist in sleep medicine at the Hirslanden Private Hospital Group, notes that sleeping in one stretch is a ‘luxury that we’ve become accustomed to’. ‘In the animal kingdom that’s extremely rare since sleeping in short spells provides better odds of survival,’ he adds. The intervals that we sleep at are part of the history of evolution and are also culturally determined. In many societies, it’s common to take a siesta in the early afternoon or to have a nap after work.
Bertrand Piccard and André Borschberg survived on power napping when they flew around the world in five days and nights in the Solar Impulse 2. In Asia many people doze in restaurants or at conferences without any sense of embarrassment. ‘Sleeping in public sends the message that you’re a very busy person,’ says Michael Wiegand from the Munich Sleep Centre (Schlafzentrum München). In Japan, a type of sleeping known as inemuri is practised. People fall asleep as if on command, but are still present in a sense; they don’t miss their stop on the train despite taking a nap.
We sleep in cycles
Although there have been attempts to prove the opposite in a wide range of experiments, we can’t live without sleep altogether. Eventually we all succumb to the need for a little shut-eye. Scientists have done extensive research into what happens while we are asleep. They distinguish between two key phases of sleep according to the activity level of the brain and the various body functions. Medical professionals speak about REM (rapid eye movement) sleep, formerly also known as ‘dream sleep’, and NREM (non-rapid eye movement) sleep, which in turn is divided into four stages. Those stages alternate repeatedly with REM sleep during the night. Each sleep cycle lasts one and a half to two hours, and we experience four to six cycles in a night’s sleep. Towards the morning, phases of REM sleep and light sleep are dominant.
Social jet lag
Whether we are ‘morning larks’ or ‘night owls’, little consideration is given to our individual biorhythm at school or at work. Till Roenneberg, professor of chronobiology at the University of Munich, coined the term ‘social jet lag’ to describe the difference between the sleep times that are ‘programmed’ in our body and those that are imposed on us by the outside world. Employees who work in changing shifts have a particularly tough time. However we’re all familiar with the daily battle against the clock. People with an extreme chronotype suffer the most, but even normal ‘night owls’ and ‘morning larks’ don’t have it easy.
This article is part of the ‘Get a better sleep’ series and was put together in cooperation with Commercial Publishing Tages-Anzeiger. See here for all articles in the series.