Little was known about sleep until modern science revolutionised our understanding. It turns out that what happens while you are unconscious dictates almost every aspect of your waking health, mood and brainpower. While knowing how to get better sleep and why you need it is vital, the nocturnal world holds some interesting secrets. Here we look at eight things you probably did not know about sleep. 1. Testy times If young men don’t get enough sleep, they have a level of testosterone that is...