Sleep debt
Sleep debt is not simply about a single bad night. It accumulates over days, and a person can feel the effects of a poor sleep pattern even if any individual night looked acceptable on its own. Wearables estimate sleep debt by comparing recent sleep duration and quality against a person's own typical need.
The effects of sleep debt on working capacity are well established: slower reaction times, reduced patience, weaker memory consolidation and a general drop in the ability to handle complex or ambiguous tasks. These effects tend to appear gradually, which is part of why sleep debt is easy to underestimate in the moment.
Sloane reads sleep data from connected wearables, where available, and treats an emerging pattern of sleep debt as a meaningful input, particularly when it coincides with a heavier-than-usual calendar. The aim is to flag the combination early, while there is still a reasonable choice to make about the week ahead.
Sleep debt is personal. Someone who normally sleeps six hours and feels well rested is not automatically in debt at six hours; someone who normally needs eight and is getting six may be. This is another reason Sloane always measures against a person's own baseline rather than a fixed number of hours.
Related terms
- Recovery score, A composite daily score, produced by a wearable, that summarises how well rested and prepared a person's body appears to be for demanding activity.
- Readiness, A daily estimate of how prepared a person is to take on demanding work, based on overnight physiological recovery relative to their own baseline.
- Circadian rhythm, The roughly 24-hour internal cycle that governs alertness, body temperature and sleep timing, and which shapes when a person naturally does their best thinking.
- Personal baseline, The rolling normal range for a specific individual across their signals, used as the point of comparison for deciding whether something has genuinely changed.