Time use diaries as a tool for measuring sleep among individuals incarcerated

To evaluate the feasibility of using time use diaries to measure sleep and characterize sleep duration and sleep-wake patterns among individuals incarcerated in jail.

Adults housed in 2 general‑population units of a Southwestern US jail completed a 4‑day, paper‑and‑pencil time use diary documenting 10-minute activity intervals. Sleep was identified using participant‑reported activities coded with the Compendium of Physical Activities. Sleep was categorized as day- or night-time based on facility schedules. Sleep pattern indicators, including wake‑time, return‑to‑sleep behavior, napping, and bedtime, were classified across valid diary days. Descriptive statistics summarized sleep duration and patterns overall and by sex assigned at jail intake.

Of 64 participants, 62 (96.9%) completed at least one valid diary day; most completed all days, yielding 238 diary days (93.0% completion). Participants averaged 630.8 minutes (10.5 hours) of total daily sleep, with 256.7 minutes (4.3 hours) of daytime sleep and 374.1 minutes (6.2 hours) of nighttime sleep. Females and males had similar total sleep duration. Over half (56.5%) of participants' sleep patterns were not aligned with institutional schedules for programming, meals, and lights out; 83.9% returned to sleep after breakfast (4:30 AM); and 53.2% napped during the day. Half of participants went to bed at lockdown (9:00 PM), while 27.4% went to bed after lockdown. Females with job assignments slept substantially less overall than females without.

Time use diaries are feasible and informative for measuring sleep among individuals incarcerated in jail. Sleep was fragmented and disproportionately accumulated during the day, reflecting structural constraints of the carceral environment. Findings underscore the need for sleep‑measurement tools tailored to carceral settings.