🌙

Shift Sleep Calculator

Enter your weekly shift pattern and get personalised sleep windows, transition advice, sleep quality scores, and nap suggestions — based on circadian science.

How the Calculator Works

Circadian-Based Sleep Windows

Sleep timing recommendations are calculated from your shift times using the same principles as circadian sleep medicine. For night shifts, the main sleep is anchored immediately after the shift ends to capture the highest sleep pressure window. For day and evening shifts, sleep windows are calculated backwards from the required wake time, targeting multiples of 90 minutes (one sleep cycle) to minimise sleep inertia on waking.

Transition Detection

The most important sleep challenge for shift workers is not any single shift — it is the transition between shift types. Your circadian clock takes 2–4 days to adapt to a new schedule, which means the first and last days of any shift block are significantly harder than the middle days. The calculator detects these transitions automatically and provides specific, evidence-based advice for each: first night back, last night before days off, first recovery day, and schedule changes between shift types.

Sleep Quality Flags

Each day is rated Optimal, Challenging, or Difficult based on the shift category and transition context. Difficult days are transition days where your circadian system is under the most stress. Knowing in advance which days will be hardest lets you plan ahead — scheduling demanding tasks away from Difficult days and prioritising recovery.

Nap Suggestions and Integration

Nap suggestions appear on days where a strategic nap can meaningfully reduce fatigue — particularly on the first night back after days off (where a pre-shift 90-minute nap significantly reduces first-night impairment) and on early-morning shift days with compressed overnight sleep. Each suggestion links to the Nap Strategy Calculator for exact timing based on your specific shift.

Weekly Sleep Debt

The week summary calculates your total sleep against a 7-hour daily target, showing how much sleep debt accumulates across the working week. Sleep debt is real and partially cumulative — cognitive impairment from chronic partial sleep loss is not fully reversed by a single recovery night. Tracking it helps prioritise recovery on days off and informs decisions about nap strategy.