Scientists have made a breakthrough in answering the age-old question: Why do we need sleep?
According to a study in the US, sleeping activates a gene which allows certain types of brain cell to be replenished.
Called myelin, the cell is vital for the role it plays in insulating the circuitry of the brain and allowing electric impulses to be fired.
Though the research has so far only been conducted in mice, it has big implications for our understanding of the impact missing out on sleep could have on the human body.
The authors of the report, which has been published in The Journal of Neuroscience, said the breakthrough could lead to further studies and in particular speculated that sleeplessness might aggravate some symptoms of multiple sclerosis (MS) – a disease which damages myelin.
In the study released today, lead scientist Dr Chiara Cirelli and colleagues at the University of Wisconsin in the US measured the activity of genes related to “oligodendrocytes”, which make myelin both as part of healthy regeneration and in response to injuries.
They found that the genes in mice that promoted myelin production were turned on during sleep.
By contrast, other genes that are involved in cell death and stress response were found to be on in mice who were forced to stay awake.
Dr Cirelli said: “For a long time, sleep researchers focused on how the activity of nerve cells differs when animals are awake versus when they are asleep.
“Now it is clear that the way other supporting cells in the nervous system operate also changes significantly depending on whether the animal is asleep or awake.”
For centuries scientists have tried to establish the precise biological processes that take place while we sleep, and the benefits the body receives.
The US National Institute of Neurological Disorders and Stroke (NINDS) told the BBC that we already knew deep sleep allows the body to recover better from harmful factors such as stress and ultraviolet rays – in other words, genuine “beauty sleep”.
Now though, it appears a good night’s rest also offers a benefit for our brains.