Why a Long Lie-In Can Leave You Feeling Worse
You've had a hard week, so on Saturday you sleep until eleven. You get up feeling groggy, vaguely unwell and worse than you did on Thursday after six hours.
This is extremely common and there are two things going on, both of them unrelated to how much sleep you needed.
One: you woke in the wrong place
Sleep runs in cycles of roughly ninety minutes. Waking at the end of one, in light sleep, is easy. Waking out of the middle of deep sleep produces sleep inertia — the thick, disoriented fog that can take half an hour or more to clear.
The longer you stay in bed, the more likely you are to eventually be woken by something arbitrary — a noise, a bladder, a person — rather than surfacing naturally at the end of a cycle. Eleven hours gives arbitrary a lot of opportunities.
Two: you moved your clock
This is the bigger one and it costs you more than Saturday.
Getting up four hours later than usual, and getting light in your eyes four hours later than usual, shifts your body clock later. On Sunday you're not tired at eleven at night. On Sunday night you lie there. On Monday you're wrecked.
Till Roenneberg called this social jet lag, and it's the reason Monday morning feels like a long-haul flight for so many people. The full explanation is on our Circadian Rhythm page.
You repaid a little sleep and borrowed a whole week of bad timing to do it.
What to do instead after a short week
Cap the lie-in at an hour. Not up at seven on a Saturday, but not eleven either.
Go to bed earlier rather than getting up later. Half an hour to an hour earlier, for two or three nights. That's roughly one extra cycle, and it's how recovery actually works.
If you need more, nap. Twenty minutes or ninety, before three in the afternoon. It tops you up without moving the clock.
The bit that's hard to accept
You cannot repay sleep hour for hour. Some recovery happens, and it happens over several ordinary nights rather than one enormous one.
Which means the most effective thing you can do after a bad week is spectacularly boring: get up at the normal time, get outside, and go to bed a bit earlier for three nights.
