Sleep pressure
health · saved from an article on sleep science
- Adenosine builds up while you're awake; sleep clears it. That buildup is what "sleep pressure" means.
- Caffeine blocks the signal but doesn't clear it. See caffeine.
- Hard training days raise how much sleep you need. See training.
Two things decide when you get sleepy
- Sleep pressure. Rises every hour you're awake and drains overnight. A short night leaves some of it behind for the next day.
- Your body clock. A roughly 24-hour rhythm, set mostly by light. It keeps you alert in the late afternoon even when pressure is high, then lets go in the evening.
You fall asleep most easily when the two line up: high pressure, and the clock winding down.
What this means in practice
- Keep wake-up time steady, weekends included. It anchors the clock more than bedtime does.
- Get daylight early. Ten to twenty minutes outside in the morning helps set the rhythm.
- Naps spend pressure. A short one before 3 pm is fine; a long late one makes the night harder.
- Caffeine hides pressure rather than removing it. When it wears off, the backlog is still there.
Questions to look into
- Does a late workout push my sleep back, or is it the screens afterwards?
- How much of my Monday tiredness is just a shifted weekend schedule?