The score combines four components: sleep duration (40 pts — NSF recommends 7–9 hours for adults), sleep latency (25 pts — falling asleep in under 10 minutes scores highest), sleep continuity (20 pts — zero awakenings is optimal), and morning freshness (15 pts — your subjective sense of restoration). Each component uses clinically-informed thresholds from sleep medicine literature.

85–100 is excellent; 70–84 is good; 55–69 is fair; 40–54 is poor; below 40 is very poor. Most healthy adults with consistent sleep hygiene score in the 70–90 range. A single night does not define your overall sleep health — track over several nights for a meaningful picture.

Sleep latency is how long it takes to fall asleep after lights out. Clinically, under 20 minutes is normal. Consistently falling asleep in under 5 minutes can signal sleep deprivation rather than good sleepiness — healthy sleep onset takes 10–20 minutes. Over 30 minutes is considered problematic and is a diagnostic criterion for insomnia.

Brief awakenings fragment sleep architecture and reduce time in restorative slow-wave (deep) and REM sleep, even if total sleep duration looks adequate. Frequent awakenings are linked to daytime fatigue, reduced cognitive performance, and elevated inflammatory markers — effects that build cumulatively over weeks of disrupted nights.