Why Do We Sleep?

By   Shlomo Maital

   Why do people sleep? For evolutionary biologists, it’s a bit of a mystery. Sleep makes us vulnerable to predators. How come people and animals did not evolve without the need for sleep?

     A new research study, just published in Nature Communications, reveals an answer. The study is by Bar Ilan University doctoral student David Zada, along with professorial co-authors.

     Until now, we did know that lack of sleep affects brain functioning. Could sleep be a biochemical process essential for life?

     The answer is yes.   Zada studied zebrafish. When they are young, they are transparent – even their skulls.   Zada could look directly into their brains.

       Here is what he found. Every human cell (except for one exception – red blood cells) has DNA. DNA gets damaged over time and needs repair within the cell. There are enzymes that do this.

         Zada found that when zebrafish sleep, their neural cells no longer need energy for waking purposes, and this frees energy for their cells to repair their damaged DNA. He used time lapse photography to show this. When fish are awake, their chromosomes have far fewer resources to engage in repairs.

         Apparently we sleep in order to engage in crucial maintenance for our neurons – nerve cells – in particular, just as my Toyota needs regular maintenance from time to time in the garage.

         So – let’s get some sleep and let our amazing bodies fix their neural cells. It is well known that teenagers in particular do not sleep enough. Maybe we can learn from the zebrafish?