The night: Your nocturnal transformation revealed

 作者:莫械     |      日期:2019-03-01 03:17:02
By Jessa Gamble Night turns us into alien creatures (Image: Kiril Standev/Gallery Stock) Read more: “The night: The nocturnal journey of body and mind“ THE transformation starts while you are still awake. Just before bedtime, body temperature plummets almost half a degree from its mid-evening peak. Melatonin, a sleep-promoting hormone, surges in response. Suddenly, the pressure to sleep that has built throughout the day no longer encounters the resistance of a high body temperature, and waves of fatigue assail you. This isn’t just your body priming you for a good night’s rest. In some ways, it is preparing you to become a whole different creature, because the night-time body has functions and a character all its own. If night never ended, we would hardly recognise what we become. The moment you succumb to sleep’s inexorable pull, your body temperature drops. The lower body heat slows chemical reactions, setting the stage for mechanisms that mend fatigued muscles and flush toxins from the brain. You are now ready enter an alternate reality, a rolling cascade of 90-minute sleep cycles. In each one, you pass through four stages of sleep, ending with the rapid-eye-movement phase that resembles the brain’s waking state and hosts much of your dreaming life. Then the cycle restarts. Most people are taken on this roller-coaster of phases for somewhere between 6 and 9 hours. This is not how we used to sleep. Before ubiquitous artificial light,