Three twelve-hour days in a row, usually 0700 to 1900, then four days off. Of the nine patterns here this is the one closest to a daylight schedule, and the only one where the work-day anchor and a normal rest-day anchor can sit within an hour of each other.
These are example times, not your times. Everything below is computed from a single pair of wake anchors: 5:00 AM on a work day and 6:30 AM on a rest day. A 5:00 AM wake puts the shift start at 0700 with time to get out the door, and a 6:30 AM rest-day anchor sits inside the hour and a half of drift the pattern can absorb. If your anchors are different, every window below shifts with them, which is what the plan builder does with your own numbers.
The plan works backward from the wake anchor rather than forward from bedtime, because bedtime is the part your schedule takes away from you. The sleep target on each day is the anchor minus the sleep opportunity; the caffeine cutoff is eight hours before that target; the last real meal is three hours before wind-down starts. So the anchor is the only number you set, and the rest falls out of it.
The three days you work. 12 hours on duty, going on shift at 7:00 AM.
| Wake anchor | 5:00 AM |
|---|---|
| Bright light | 5:00 AM to 6:30 AM |
| Caffeine | 6:00 AM to 6:30 AM (first cup), stop by 1:00 PM |
| Last real meal | by 4:30 PM |
| Wind-down | 7:30 PM to 8:00 PM |
| Sleep target | 9:00 PM |
Your days off.
| Wake anchor | 6:30 AM |
|---|---|
| Bright light | 6:30 AM to 8:00 AM |
| Caffeine | 7:30 AM to 8:00 AM (first cup), stop by 2:30 PM |
| Last real meal | by 6:00 PM |
| Wind-down | 9:00 PM to 9:30 PM |
| Sleep target | 10:30 PM |
A 12 that starts at 0700 puts your wake anchor near 0500, which is early enough that a full sleep opportunity has to start before most people have finished dinner. That is the squeeze: the pattern is aligned to daylight but shifted early inside it. Then the four days off arrive and there is nothing forcing the anchor, so it drifts. The engine gives this pattern only two day-types, work and rest, because there is no turnaround to plan around — which means everything rests on how far apart you let those two anchors get.
Day 12s are the easiest pattern to keep aligned and the easiest to wreck on days off. Keep your rest-day anchor within about an hour of your work-day anchor. The temptation to sleep until noon on the first day off is the single thing that makes the first shift back feel like a night shift.
Eight hours before the sleep opportunity you are protecting. In the worked example on this page, a 5:00 AM wake anchor on a work day puts the sleep target at 9:00 PM, so the last caffeine of any kind lands at 1:00 PM. Move the anchor and the cutoff moves with it — the eight hours is the rule, not the clock time.
The plan sets the sleep target backward from the wake anchor rather than forward from the end of a shift. In the example here, a 5:00 AM work-day anchor gives a 9:00 PM sleep target, with wind-down starting at 7:30 PM. On a rest day the 6:30 AM anchor gives a 10:30 PM target.
Within 90 minutes of waking, whatever the sun is doing. In the worked example that is 5:00 AM to 6:30 AM on a work day. Ten to fifteen minutes is enough. Then keep bright light off you in the three hours before the sleep target.
Finish the last real meal three hours before wind-down starts — 4:30 PM on a work day in this example, given the 7:30 PM wind-down. After that keep it small and boring rather than nothing at all.
The plan builder takes six questions — your pattern, your two wake times, your last cup of coffee — and computes the same windows against the schedule you actually work, as a visual timeline for each kind of day. Free, printable, no account.
Build my free sleep planEvery window on this page comes from one of a handful of rules, and the Shift Worker's Field Manual is where those rules are laid out with their sources: why the wake anchor is the lever rather than bedtime, what light does to the body clock and when, the eight-hour caffeine cutoff and where it comes from, and what to do when the problem is bigger than a schedule.
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