Person-level And Daily Associations Of Recreational Sedentary Screen Time With Sedentary Time, Physical Activity, And Sleep

Recreational sedentary screen time (rSST), refers to time spent watching screens (TV, smartphones, video games) while sitting/lying, and is the most prevalent discretionary sedentary behavior (not for work or education) and is strongly linked to poor health outcomes. Uncovering the interrelatedness of rSST, other sedentary time (ST), standing (SD), light-to-moderate-vigorous physical activity (LPA), moderate-to-vigorous physical activity (MVPA), and total sleep time (SL) is necessary to understand the daily relationships between 24-hour behaviors. Few studies have examined how rSST is related to other 24-hour behaviors (ST, SD, LPA, MVPA, SL), and no studies have used device-based measures. PURPOSE: This work assessed daily associations between rSST and 24-hour behaviors, and variations with age, sex, chronotype, and week- or weekend days. METHODS: Baseline data from 87 participants enrolled in the StandUPTV study were included (mean age: 41.4 ± 11.7 yrs; 79% female). The 16-wk intervention study aimed to reduce rSST in adults reporting >3 h/day. Device-based measures assessed associations between rSST and 24-hour behaviors. A multilevel model approach was used to assess between- and within-person associations of rSST with same-day 24-hour behaviors. Age, sex, chronotype, and week vs. weekend day were tested moderators. RESULTS: There were negative associations at between- and within-person levels for rSST with 24-hour behaviors. Negative associations were found: at the within-person level and stronger on weekdays between rSST and SD (b = -0.1, SE = 0.1, p = 0.02) and LPA (b = -0.1, SE = 0.1, p = 0.02); between rSST and MVPA, and stronger with younger than older adults (b = -0.02, SE = 0.01, p = 0.02) at the within-person level; between rSST and ST at the between-person level, and stronger on weekdays (b = -0.1, SE = 0.1, p = 0.02); and between rSST and ST at the within-person level, that was stronger with younger than older adults (b = -0.2, SE = 0.1, p = 0.02). CONCLUSIONS: Daily increases in rSST were associated with less ST, suggesting rSST may displace other ST rather than contributing to more cumulative ST. This work assessed rSST and 24-hour behaviors with devices, which has rarely occurred before. Further work is needed using device-based measures to better understand the influence of rSST on other 24-hour behaviors. R01CA239612