Make the number make sense.
Short, practical explanations of the model behind the calculator, the limits of cycle-based planning, and the questions that matter more than a perfect bedtime.
How sleep cycles work
What a 90-minute cycle means, why it varies, and how to use it as a planning model.
Sleep duration by age
A clear reference table for children, teenagers and adults, with source links.
How to take a better nap
Short naps, full-cycle naps and the trade-offs that matter in the afternoon.
How this calculator works
The exact formula, the assumptions behind it, and what it cannot tell you.
Shift work guides
For night shifts, long shifts and rotating schedules where the usual bedtime advice does not fit.
Night shift nurse sleep schedule
A practical planning example for a 19:00–07:00 shift.
12-hour shift sleep schedule
How to protect sleep around a long shift and commute.
Rotating shift sleep schedule
Planning principles for schedules that keep changing.
Night shift recovery sleep
How to plan the first sleep after a run of night shifts.
Shift worker nap schedule
Timing short naps around a shift without losing the main sleep window.
How to sleep before a night shift
A practical before-shift routine with a shift-start table and protected wind-down time.
Night shift meal and caffeine schedule
How meal timing, caffeine and hydration fit around a night shift.
How to stay awake on a night shift safely
Light, movement, breaks and driving safety without pretending a calculator is a medical check.
Three nights in a row: shift sleep plan
A repeatable three-night example with recovery-day planning.
When shift work sleep problems need professional help
Warning signs, records to keep and questions to ask a qualified professional.