Nine habits, ranked by minutes gained
We tested what volunteers actually changed. The winners were boring: a fixed wake-up, a cold dark room and a phone in the hall.
The ranking
Phone outside the room: +34 minutes. Fixed wake-up time, seven days a week: +27. Bedroom under 19°C: +18. No caffeine after 14:00: +12. Blackout blinds for day sleepers: +41, the biggest single change for night-shift workers.
What did nothing
Sleep-tracking apps on their own, magnesium supplements and ‘wind-down’ playlists made no measurable difference in our sample. White-noise machines helped only in cities.
What people kept
A month later, 61% of those who moved the phone out were still doing it. Only 22% kept the 14:00 caffeine rule.
What we would test next
Next winter we will follow 300 of the same volunteers through a clock change, and add light sensors to the ring so we can see what the evening actually looks like.
The chart
Hours asleep with and without the phone in reach.
Key findings
Three numbers to take away.
Phone outside the room: +34 minutes.
Fixed wake-up time: +27 minutes.
Blackout blinds for day sleepers: +41 minutes.
Sleeper diaries
