Log your sleep each morning. See weekly patterns. All data stays on your device — nothing is sent anywhere. AASM-recommended format for CBT-I.
A sleep diary is the most powerful and underutilized sleep improvement tool available. Most people assess their sleep quality through subjective impressions that are notoriously unreliable — studies consistently show that people's recall of how they slept is biased by their most recent awakening and their general mood. Systematic daily logging captures patterns that subjective impression misses completely: which nights are consistently better, what behaviors correlate with better sleep, and whether interventions are working.
Two weeks of sleep diary data reveals patterns that are invisible without tracking. Common discoveries: sleep quality is dramatically better or worse on certain days of the week (often reflecting alcohol, late social events, or work stress); there is a consistent relationship between caffeine timing and sleep quality; sleep consistently improves when a specific behavior changes; the actual sleep duration is consistently different from the perceived duration; and variations in bedtime have little impact on morning energy — but variations in wake time are highly correlated with how you feel.
These patterns are essentially impossible to identify from memory alone. The human brain is not designed to accurately track and correlate 14-night datasets — the sleep diary does it automatically through visual pattern detection in the weekly chart.
The sleep diary is the assessment backbone of CBT-I (Cognitive Behavioral Therapy for Insomnia). At the first session, patients complete 2 weeks of baseline diary before any intervention begins. This establishes actual sleep patterns rather than perceived ones. Throughout the 6–8 week program, the diary tracks response to each intervention — sleep restriction, stimulus control, cognitive restructuring — allowing the therapist to adjust the protocol based on objective data. Our format follows the AASM-recommended sleep diary structure used in clinical practice.
The most important rule: fill it in the morning, not during the night. Looking at the clock during the night increases arousal and anxiety. Morning estimates from recall are accurate enough for pattern detection and are the standard approach in all clinical sleep diary studies. Don't strive for perfect precision — estimate to the nearest 15 minutes. What matters is consistent measurement, not perfect accuracy. Log every night for at least 2 weeks before drawing any conclusions.