Sleep Duration Basics: Clocks, Targets, and 90-Minute Cycles
Computes elapsed sleep from bedtime to wake (crossing midnight when needed), divides by 90 minutes for an educational cycle count, and subtracts your target hours. This guide explains the worksheet assumptions in plain language.
Formula in plain language
durationMinutes = wakeClock − bedClock (add 24h if wake ≤ bed); durationHours = minutes ÷ 60; cycles = minutes ÷ 90.
What this is not
Educational worksheet only—not a diagnosis or sleep-medicine advice. Target hours are your assumption. Confirm concerns with a clinician.