What time should I go to bed if I wake up at 10:00 pm?

Waking at 10:00 pm is a night-shift schedule: sleep runs through the day, with lights out at 2:15 pm for five cycles or 12:45 pm for six.

Why three times and not one

The middle option, 2:15 pm, is five cycles and 7 h 30 min of actual sleep; 12:45 pm is six cycles and 9 h. Both sit inside the adult range. The 3:45 pm option is 6 h: enough to get through the day, not enough to do it twice.

The three times are ninety minutes apart because that is the average length of one trip through light, deep and REM sleep. Real cycles vary — 70 to 120 minutes, shorter early in the night — which is why 2:15 pm is a target and not a deadline.

Here is the shape of the night. You settle at 2:15 pm and are asleep by 2:30 pm; the first and deepest slow-wave stretch arrives near 2:50 pm; by 6:15 pm you are halfway through; from about 9:25 pm the final REM period runs up to the 10:00 pm alarm. Cut the night short and that last REM block is what goes.

All bedtimes for a 10:00 pm alarm

Formula: bedtime = wake time − (cycles × 90 min) − 15 min · adult range from the NSF 2015 panel and the AASM/SRS 2015 consensus · methodology

10:00 pm: the alarm for midnight starts

Some work begins at midnight or 1 am: overnight freight, wholesale markets, parcel sorting, the first bakery shift. For those jobs a 10:00 pm alarm is an ordinary morning, and the bedtimes are 2:15 pm for five cycles, 12:45 pm for six and 3:45 pm for four. Compared with a standard night shift this schedule has one advantage: the sleep ends just before work, so you start fresh and have been awake only 9 hours at 7 am.

It also has a specific weakness. A 2:15 pm bedtime falls in broad daylight all year, and mid-afternoon into evening is when a body on normal time resists sleep most; reviews of shift work describe the same trouble on early-morning shifts, where people cannot get to sleep early enough and end up short. Expect the fifteen minutes this site allows for falling asleep to stretch, and lean toward the earlier 12:45 pm bedtime to absorb it. Blackout blinds are not optional at this hour. School traffic and evening noise fall inside your sleep, so sound masking earns its place. The caffeine line is 8:15 am, which rules out a coffee at the end of the shift. On days off most people drift back toward night sleep; decide in advance whether you keep 2:15 pm or switch back, and if you switch, use the last day off to move toward it again.

Every alarm in the 10 pm hour

Lights-out times for each alarm · last coffee = six hours before the five-cycle bedtime (Drake 2013) · full grid on the open data page

If you can't fall asleep by 2:15 pm

If 2:15 pm comes and your mind is still running, aim for the next cycle boundary at 3:45 pm instead of counting the minutes. Ten to twenty minutes to fall asleep is normal; much longer, repeatedly, is worth a conversation with a clinician rather than a calculator.

Try a different time