Science & sleeping
Prof Dr Matthew Walker has been doing scientific research on the function of sleep for over two decades. Sleep consists of several sleep cycles and if you don't sleep at least 7-8 hours then not all cycles are completed. With insufficient sleep, the immune system is not activated and can even backfire. Many studies show that between 40-50% of the population suffers from poor sleep and that this underlies many health complaints.

- Sleep is an important prerequisite for healthy ageing.
- Lack of sleep lowers performance: lower productivity, social sensitivity, rational decision-making, memory recall, emotional control, testosterone, immune system etc.
- All major diseases - Alzheimer's, cancer, obesity, diabetes - are strongly linked to sleep deprivation.
- Regularly sleeping less than 7 hours is as bad as smoking and drinking.
- In all industrialised countries, the number of hours of sleep has fallen dramatically and the incidence of mental illness and disorders has risen the fastest.

Sleep is one of the most puzzling human behaviours about which science remains ignorant. Looking at the question from an evolutionary perspective only adds to the mystery. A completely weird biological phenomenon. Because while you sleep, you can't forage for food. You can't socialise. You can't reproduce while you sleep. You cannot nurture or protect your offspring. You are vulnerable to predators. Riddle me this. Every species studied to date sleeps. 

There is no single reason why we sleep. In our brains, sleep contributes to a multitude of functions, including our ability to learn, our memory, and the ability to make logical decisions and choices. Sleep recalibrates our emotional circuits in our brains, allowing us to cope with our social and psychological challenges during the day. Dreams are also important, in which brains merge old and new knowledge: our creativity.Sleep is also important for our immune system. the weapons used to fight cancer, prevent infections and ward off disease, among other things. It recalibrates our emotions, builds our immune system, affects our metabolism and even regulates our appetite.

"If you regularly sleep less than seven hours, it kills your immune system and more than doubles your risk of cancer"

Sleep problems occur in 40-50% of the population and in all strata and ages. Interestingly; they are most common in the elderly and 2x more in women than men.

- Humans do not sleep as nature intended. Instead of the monophasic pattern (one long, single period of sleep), we should sleep in a two-phase pattern (seven to eight hours in bed, followed by a 30- to 60-minute nap in the afternoon).
- Sleep before learning refreshes our ability to make new memories in the first place. Sleep after learning effectively clicks the "save" button on the newly acquired information.
- Lack of sleep has the property of accumulating.
- Practice does not make perfect. It is practice followed by a night's sleep that leads to perfection.
- During REM sleep, the smartest creative ideas come to us.
- The major factors that have greatly changed how much and how well we sleep: (1) constant electric light, (2) temperature regulation, (3) caffeine, (4) alcohol and (5) alarm clocks.