Margen
Saturday, 3:10. You turn the light off after the third episode. On Sunday you get up at 12:40 and feel rested. That night, at 0:30, you’re lying in bed staring at the ceiling, not remotely sleepy. And on Monday at 7:15 the alarm goes off and your head feels like you’ve flown halfway across the Atlantic. And you haven’t left your room.
A week ago, in the early hours of 25 October, 3:00 turned into 2:00, and I bet someone in your class spent Monday moaning about how tired they were. One hour. You do two or three every weekend and it never makes the news.
A German who has spent his whole life studying sleep, Till Roenneberg, calls it social jet lag. It’s the gap between when your body sleeps if you let it and when school or work make it sleep. His team in Munich has been collecting a sleep questionnaire for years that more than 130,000 people have now filled in, and in 2012 Roenneberg said that two out of three people in Western countries carry a significant mismatch between the two.
And at your age it’s worse. In 2004, with 25,000 surveys, the same team found that bedtime keeps getting later all through adolescence and peaks right about now: at nineteen and a half for girls and almost 21 for boys. After that you go to bed a bit earlier every year without trying. Roenneberg said it was the first time anyone could mark the end of adolescence with a number.
So you’re not lazy for sleeping till one. At 19 your body clock runs later than your parents’. The problem is that on Monday the alarm still goes off at 7:15.
What happens in between is a return flight. At 0:30 on Sunday, for your body it’s more or less half nine in the evening: no wonder you can’t drop off. At 7:15 on Monday, for it, it’s just gone four in the morning. By Tuesday you’ve made half the trip back, just in time to undo it on Friday.
The 2012 study also found that the more social jet lag people had, the higher their body mass index, the number for your weight against your height. That doesn’t prove one causes the other, mind.
I’m sure about this one, and I’m telling my flatmate tonight, because she got up at half two on Sunday: at the weekend, don’t get up more than two hours later than on weekdays. If your Monday alarm is 7:15, set Sunday’s for 9 even if you went to bed at 3, and if you’re falling asleep, a short nap after lunch. You sleep less that Sunday, yes. But that night you get sleepy at your normal time and on Monday you’re not landing from anywhere.