Nairobi, March 15 -- Sleep is as essential to our health as food and water. It is important to a number of brain functions, including how nerve cells communicate with each other. We sleep for a third of our lives and there are many restorative processes going on during sleep that are needed to stay healthy.

Why do we usually sleep at night? What happens when we don't sleep? On World Sleep Day, Nadine Dreyer asks a group of experts to tell us more about this essential part of our lives.

Why do we need sleep and why do we sleep better at night?

We sleep for a third of our lives, yet it is only when we cannot sleep or when we experience poor quality sleep that we really start noticing it.

During sleep, our muscle activity drops, our brea...