Sleep

Bedtimes, wake times, sleep debt, naps and caffeine.

• Caffeine Calculator How much caffeine is left in your body at bedtime, from a dose, the time you had it and its half-life.
• Nap Calculator When to wake from a nap of each length, and the latest sensible time to nap before bed.
• Sleep Calculator Bedtimes for a set wake-up time, or wake-up times for a set bedtime, in 90-minute sleep cycles.
• Sleep Debt Calculator How far short of your sleep need you fell, over up to seven nights.