There is quite a bit of evidence about the negative health consequences of insomnia, but researchers don’t know precisely what it is in the brain and body that is “restored” by sleep to aid optimal function. And it is unlikely that any specific stage of sleep is uniquely restorative, said Dr. Daniel J. Buysse, a sleep medicine expert and professor of psychiatry at the University of Pittsburgh. More sleep, less interrupted sleep, and sleep at the right time of night are all likely to be important, he said. To read more….