chronotype: lion, bear, wolf or dolphin
Most chronotype tests ask you questions. RestUp reads the answer off your watch, from when you actually fell asleep and woke up, night after night.
What is a chronotype?
A chronotype is the time of day your body naturally prefers to sleep and wake, driven by your internal clock rather than by your alarm. Sleep researchers usually describe it with a single number, the midpoint of your sleep, because it is easy to measure and shifts reliably between early and late types. RestUp estimates your chronotype on your phone from at least a week of recorded nights: it takes the midpoint between falling asleep and waking on each night, averages those midpoints around the clock, and corrects for nights where you slept more or less than your target, building on the mid-sleep approach Till Roenneberg and colleagues introduced in 2003. Roenneberg’s own correction adjusts free-day mid-sleep for your average sleep across the week; RestUp corrects against your sleep target instead. The result is expressed as one of four animals, lion, bear, wolf or dolphin, and used to suggest a wind-down time that fits you rather than a generic bedtime.
How RestUp reads yours
- Mid-sleep point. For every night with a bedtime and a wake time, RestUp finds the middle of the night. A 23:30 to 07:30 night has a mid-sleep of 03:30.
- Circular average. Times wrap around midnight, so the average is taken on a clock face, not on a number line. Otherwise 23:00 and 01:00 would average to noon.
- Sleep-length correction. Nights where you overslept or underslept your target are shifted by half the difference, so a lie-in does not make you look later than you are.
- Confidence. RestUp needs at least seven nights before it says anything, and its confidence keeps rising until about fourteen. It also drops when your bedtimes are all over the place, because an average of chaos is not a chronotype.
One honest limitation: the textbook method uses only free days, when no alarm decides your wake time. RestUp uses every recorded night, so if your weekday alarm is much earlier than your body would choose, your estimate will lean slightly earlier than a pure free-day reading. Social jet lag, below, is where that gap becomes visible.
The four animals
- Lion: corrected mid-sleep before about 2:00 in the morning. In bed early, up early, best in the first half of the day.
- Bear: mid-sleep between roughly 2:00 and 3:30. The most common type, in step with daylight and a standard working day.
- Wolf: mid-sleep after about 3:30. Late to feel sleepy, slow to start, strongest in the evening.
- Dolphin: not a timing type but a pattern: bedtimes that vary by more than an hour night to night, combined with lower sleep efficiency. RestUp labels this with lower confidence, because an irregular sleeper can still be an early or a late type underneath.
| Type | Corrected mid-sleep | Roughly |
|---|---|---|
| Lion | Before 2:00 | Asleep before 22:00, awake before 6:00 |
| Bear | 2:00 to 3:30 | Asleep 22:00 to 23:30, awake 6:00 to 7:30 |
| Wolf | After 3:30 | Asleep after 23:30, awake after 7:30 |
| Dolphin | Any | Bedtimes varying by more than an hour, with low sleep efficiency |
The animals are a friendly shorthand, not a scientific taxonomy. Underneath they are just bands on the mid-sleep clock.
How RestUp uses it
Your chronotype sets the wind-down suggestion on the Sleep screen and shapes the Sunday digest. It does not change the readiness score directly; readiness cares about consistency, which is a separate measure of how similar your nights are to one another, whatever time they centre on.
Sources
- Roenneberg T, Wirz-Justice A, Merrow M (2003). Life between clocks: daily temporal patterns of human chronotypes. Journal of Biological Rhythms 18(1):80–90. Mid-sleep on free and work days as a measure of chronotype.
- Wittmann M, Dinich J, Merrow M, Roenneberg T (2006). Social jetlag: misalignment of biological and social time. Chronobiology International 23(1–2):497–509.
- RestUp’s rules:
chronotypeDetector.tsandsocialJetLag.tsin the app, summarised on this page.