Early birds may be chipper in the morning, but they mentally wear out faster, a new brain-scan study reveals. Scientists monitored the brain activity of self-described early birds and night owls in a sleep lab.
The team, led by Christina Schmidt of the University of Liège in Belgium, also took hourly saliva samples to measure the sleepers' levels of melatonin, a hormone thought to help naturally regulate sleep cycles in mammals.
Both night owls and early birds were allowed to stay on their preferred sleep schedules, but each group was awake for the same number of hours each day. Read the entire article.