Twelve-hour shifts on a two-week cycle: two on, two off, three on, two off, two on, three off — then the same pattern with the roles reversed. No work run is longer than three shifts, and no break is longer than three days. You end up with every other weekend off, which is the reason the pattern gets adopted.
These are example times, not your times. Everything below is computed from a single pair of wake anchors: 5:30 AM on a work day and 7:00 AM on a rest day. A 5:30 AM wake puts the shift start at 0730 on the day half of the rotation, and a 7:00 AM rest anchor keeps the breaks within about ninety minutes of 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 two- and three-day runs. 12 hours on duty, going on shift at 7:30 AM.
| Wake anchor | 5:30 AM |
|---|---|
| Bright light | 5:30 AM to 7:00 AM |
| Caffeine | 6:30 AM to 7:00 AM (first cup), stop by 1:30 PM |
| Planned nap | 9:30 AM to 11:00 AM |
| Last real meal | by 5:00 PM |
| Wind-down | 8:00 PM to 8:30 PM |
| Sleep target | 9:30 PM |
The short breaks between runs.
| Wake anchor | 5:30 AM |
|---|---|
| Bright light | 5:30 AM to 7:00 AM |
| Caffeine | 6:30 AM to 7:00 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 |
The long break in the cycle.
| Wake anchor | 7:00 AM |
|---|---|
| Bright light | 7:00 AM to 8:30 AM |
| Caffeine | 8:00 AM to 8:30 AM (first cup), stop by 3:00 PM |
| Last real meal | by 6:30 PM |
| Wind-down | 9:30 PM to 10:00 PM |
| Sleep target | 11:00 PM |
Nothing in this cycle lasts long enough to adapt to. A two-day run ends before a body clock has moved, and a two-day break ends before it has moved back. If the version you work turns over between days and nights, that limit is the whole story: you are never fully on either schedule, and there is no run long enough to get there. That is an argument for keeping the two anchors close together rather than swinging between them, which is what the engine does here — it builds the short two-day break as its own day-type with a nearly full sleep opportunity held near the work anchor, and saves the wider rest anchor for the three-day break.
Panama 2-2-3 never leaves a block long enough to fully adapt to. That is an argument for keeping your work-day and rest-day anchors close together rather than swinging between them. Use the two-day breaks to hold steady and the three-day break to catch up, not to reinvent your schedule.
Eight hours before the sleep opportunity you are protecting. In the worked example on this page, a 5:30 AM wake anchor on a work day puts the sleep target at 9:30 PM, so the last caffeine of any kind lands at 1:30 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 5:30 AM work-day anchor gives a 9:30 PM sleep target, with wind-down starting at 8:00 PM. On a rest day the 7:00 AM anchor gives an 11:00 PM target.
Within 90 minutes of waking, whatever the sun is doing. In the worked example that is 5:30 AM to 7:00 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.
One nap, taken on purpose, four to five and a half hours after waking — 9:30 AM to 11:00 AM in the worked example on this page. Twenty to thirty minutes, or a full ninety. Anything in between leaves you groggy.
Two-day break inside the cycle 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 5:30 AM, with the caffeine cutoff at 2:30 PM and the last real meal by 6:00 PM.
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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