Brain, heart, liver: How your sleep affects your health

he body needs sleep at night to fully rest. While the mind shuts out the day, the brain clears waste, hormones reset, immune signals shift, metabolism is recalibrated and tissues move through cycles of repair.

That is why sleep researchers are asking a larger question: does poor sleep leave a biological trace over years.
A large study of nearly five lakh UK Biobank participants, published in Nature, has added weight to that question. It found that both short and long sleep were associated with signs of faster biological ageing across several organs and molecular systems.