Three twelve-hour nights in a row, usually 1900 to 0700 or 1800 to 0600, then four days off. The three nights sit back to back, which is the part that makes the pattern workable: you are asking your body to hold one sleep schedule for three days rather than flipping it every other day. The days off are where it comes apart, because a normal day schedule is right there waiting.
These are example times, not your times. Everything below is computed from a single pair of wake anchors: 3:00 PM on a work day and 9:00 AM on a rest day. A 3:00 PM wake puts the 12-hour night starting at 1800 three hours after you get up, and leaves the sleep opportunity in the darkest part of the morning after it. 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 nights you work, back to back. 12 hours on duty, going on shift at 6:00 PM.
| Wake anchor | 3:00 PM |
|---|---|
| Bright light | 3:00 PM to 4:30 PM |
| Caffeine | 4:00 PM to 4:30 PM (first cup), stop by 11:00 PM |
| Planned nap | 7:00 PM to 8:30 PM |
| Last real meal | by 2:30 AM |
| Wind-down | 5:30 AM to 6:00 AM |
| Sleep target | 7:00 AM |
The morning you come off the block.
| Wake anchor | 3:00 PM |
|---|---|
| Bright light | 3:00 PM to 4:30 PM |
| Caffeine | 4:00 PM to 4:30 PM (first cup), stop by 2:00 AM |
| Planned nap | 7:00 PM to 8:30 PM |
| Last real meal | by 5:30 AM |
| Wind-down | 8:30 AM to 9:00 AM |
| Sleep target | 10:00 AM |
Your days off between blocks.
| Wake anchor | 9:00 AM |
|---|---|
| Bright light | 9:00 AM to 10:30 AM |
| Caffeine | 10:00 AM to 10:30 AM (first cup), stop by 5:00 PM |
| Last real meal | by 8:30 PM |
| Wind-down | 11:30 PM to 12:00 AM |
| Sleep target | 1:00 AM |
The block itself is the easy half. Three nights running means one wake anchor held for three days, and the plan below only has to survive that. What the structure takes from you is the boundary at each end. You come off the last night owing a sleep debt and facing a full day of daylight, and everyone you live with is on the opposite clock. The engine handles that with a separate transition day-type: a short sleep aligned to the block rather than a full day sleep, which is what lets you go to bed that evening instead of at noon the next day.
Treat your three nights as one continuous time zone. Do not flip back to a day schedule on the middle days off inside the block; you will pay for it on the next shift. Your bedroom has to be dark enough that you cannot see your hand, cool, and quiet enough that the house waking up does not reach you. Blackout the window properly rather than draping something over it, and run a fan or white noise loud enough to cover doors and traffic.
Eight hours before the sleep opportunity you are protecting. In the worked example on this page, a 3:00 PM wake anchor on a work day puts the sleep target at 7:00 AM, so the last caffeine of any kind lands at 11:00 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 3:00 PM work-day anchor gives a 7:00 AM sleep target, with wind-down starting at 5:30 AM. On a rest day the 9:00 AM anchor gives a 1:00 AM target.
Within 90 minutes of waking, whatever the sun is doing. In the worked example that is 3:00 PM to 4:30 PM on a work day. Ten to fifteen minutes is enough. Then keep bright light off you in the three hours before the sleep target.
One nap, taken on purpose, four to five and a half hours after waking — 7:00 PM to 8:30 PM in the worked example on this page. Twenty to thirty minutes, or a full ninety. Anything in between leaves you groggy.
Last night into first day off is planned as its own kind of day rather than a normal one. In the example, it runs on a shorter sleep opportunity ending at 3:00 PM, with the caffeine cutoff at 2:00 AM and the last real meal by 5:30 AM.
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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