Who took part, and when the lights went out
1,412 people, 38,114 nights, and the first surprise: bedtime is a range, not a time.
Who the 1,412 are
Volunteers came through three sleep clinics, two universities and five employers in twelve countries. We asked for range, not balance: new parents, night-shift workers and students are over-represented so each group is large enough to say something about.
Everyone wore the same ring for 27 nights and wrote two lines every morning: what kept them up, and how they felt on waking.
Bedtime is a range
Ask people when they go to bed and they give a time. The ring gives a spread. The typical sleeper’s own bedtime moved by 71 minutes across the study, and only one in nine went to bed within half an hour of the same time on most nights.
Across everyone, the middle 80% fell asleep between 22:05 and 01:39.
The midnight line
Half of our day sleepers were asleep by 23:47. Students pull the curve late; retirees and new parents pull it early. Founders are the only group whose median sits after midnight on weekdays.
Night shifts, set apart
141 night-shift workers sleep after sunrise, usually between 08:00 and 14:00. Their nights are shorter, 5h 26m at the median, and far more broken: daylight, deliveries and school runs arrive in the middle of them.
The chart
Bedtime for 1,271 day sleepers; each dot is one person’s median over 27 nights. Night-shift workers sit apart.
Key findings
Three numbers to take away.
Bedtime moved by 71 minutes for the typical sleeper across 27 nights.
The middle 80% fell asleep between 22:05 and 01:39.
Night-shift workers slept a median 5h 26m, the shortest of any group.
Sleeper diaries
