One of the two mechanisms regulating sleep and wakefulness is a homeostatic mechanism related to sleep pressure. It works by accumulating a chemical called adenosine in our brain the moment we open our eyes in the morning and become active. The longer we remain awake and the more active we are, the more adenosine our body produces . Its levels could even be considered a proxy for our daily activity. As a result of increased adenosine levels in the brain, the chemical pressure to sleep increases. This pressure is called sleep pressure. For most adults, it occurs after 12-16 hours of wakefulness. But what happens if this pressure doesn't arrive, or worse, we try to combat it ourselves, for example, with the blue light of a new smartphone or laptop screen, or with another cup of coffee to finish a crucial project at work?

And here's the problem... Because while the purchase of new equipment can be divided into interest-free installments, the repayment of which won't affect our household budget, the so-called "sleep debt" is a very expensive investment for our bodies.

The human brain is capable of eliminating all the adenosine accumulated during the day. Sleep is an excellent tool for this purpose – and only SLEEP . Ideally, sleep should last 7-9 hours, be effective, and include an appropriate amount of deep sleep. Only during sleep does the brain cleanse itself of adenosine. Similarly, if we sleep too little, too lightly, or if sleep is interrupted, some of the adenosine accumulated the previous day remains in the brain, acting as an overdue debt. This disturbed sleepiness balance remains with us the following day. And if even minimal sleeplessness is repeated in subsequent cycles, the debt will grow and grow, and we will have an increasingly difficult time repaying it. This leads to a state of chronic sleep deprivation, followed by chronic fatigue, which may be accompanied by symptoms of illness – both physical and mental.

Aleksandra Karykowska,

chronobiologist and member of the Sleep Research Society