In short answer: YES, you can wear your WHOOP strap for sleep and recovery only. However, since the strap is designed for 24/7 use, it’s recommended to keep your strap on regularly (if possible).
How does WHOOP make up for missing data?
WHOOP is designed for use by real people, with everyday circumstances that can likely prevent 24/7 wear. Therefore, our system is built to withstand reasonable periods of missing data, such as the duration of games where league rules or athlete preferences prohibit in-game usage. When a significant period of Strain is missing (such as competition or workout), WHOOP never attempts to guess or default the Strain. Instead, this missing data introduces inaccuracies in two areas for the day on which it takes place.
First area: Day Strain. A user's calculated Day Strain will be lower than their true physiological Strain because they will receive 0 credit for the time period they weren't wearing their strap.
Second area: Sleep Coach. Due to the low Day Strain, Sleep Coach will show a lower Sleep Need recommendation (than what the user actually needs). In response to this, an athlete may then spend more time in bed in proportion to the day's perceived strain.
NOTE: WHOOP Recovery does not take Strain or Workout data as an input. WHOOP can detect the down-stream impact of Strain on Heart Rate Variability (HRV) and other Recovery metrics with the same accuracy level as if the athlete had never taken the strap off.
What this means: Even though Day Strain and Sleep Coach were "off" during the day of the missed Strain, by the time the athlete wakes up the next morning, their WHOOP data will be reinstated as a fully-functioning system.