Calculate your sleep efficiency before starting

Track your actual sleep time versus time in bed for one week — the gap is the starting point for restriction.

Why it works

Sleep efficiency (actual sleep time divided by time in bed, as a percentage) is the key metric for sleep restriction therapy. A healthy sleeper has efficiency around 85–90%. An insomniac commonly has 60–70% efficiency: spending eight hours in bed but sleeping only five or six. The gap represents time spent awake in bed, which conditions the brain to associate the bed with wakefulness and arousal — the core maintaining mechanism of chronic insomnia.

How to do it

1. For seven days, log the time you got into bed, the estimated time you fell asleep, any wake periods, and the time you got up.
2. Calculate: (total sleep time / total time in bed) × 100 = sleep efficiency percentage.
3. Average across the week to get your baseline efficiency.

Evidence

Sleep efficiency as a metric for insomnia severity is standard in sleep medicine; the baseline calculation is the entry point for all CBT-I sleep restriction protocols. (clinical)

Self-report sleep logs are imprecise; they are sufficient for clinical guidance but will not capture exact sleep architecture. Consumer wearables add light-effort objective data but their sleep-stage accuracy is limited.

Sources

• Spielman, Saskin & Thorpy (1987), treatment of chronic insomnia by restriction of time in bed, Sleep

Common mistake

Estimating from memory rather than prospective logging — memory of sleep is notoriously inaccurate, and insomniac patients systematically underestimate their sleep time.