Bidirectional associations of recreational sedentary screen time and 24-h behaviors: a dynamic cross-sectional...

Recreational sedentary screen time (rSST) is the most prevalent form of discretionary sedentary behavior and is strongly linked to poor health outcomes. However, the relationship between time spent in rSST and other 24-h behaviors is not well understood. The purpose of this study was to examine between- and within-day associations between rSST and other 24-h behaviors that include other non-rSST sedentary time (other-SED), standing (STAND), light physical activity (LPA), moderate-to-vigorous physical activity (MVPA), and total sleep (SLEEP).

Baseline data from participants randomized to the StandUPTV study, an intervention aimed to reduce rSST in adults, were included. All 24-h behaviors were assessed continuously for 7-days. The activPAL device was used to assess rSST, other-SED, STAND, LPA, and MPVA; SLEEP was assessed using a GENEactiv accelerometer. rSST was collected using Wi-Fi plugs to capture TV time and tablet app usage. A multilevel modelling approach was used to assess bidirectional associations between rSST (total, daytime, evening) and 24-h behaviors at the between-person (across persons) and within-person (across days) levels, adjusting for age, sex, chronotype, education level, and week versus weekend day. The results were scaled hourly for interpretation.

On average, 8.0 ± 1.6 days of continuous daily 24-h behavior data were included from 94 participants (age [M ± SD: 42.3 ± 11.5] years; 82% female; 78% White; BMI [M ± SD: 29.8 ± 7.8] kg/m²). Greater total rSST was significantly associated with less other-SED (between-person b =  - 45.0, SE = 4.4, p < 0.01; within-person b =  - 44.5, SE = 2.0, p < 0.01). Similar results were observed when examining both daytime and evening rSST with other-SED. Negative associations were also observed between other-SED, STAND, LPA, and MVPA with rSST variables. No significant associations were observed between rSST variables and SLEEP.

This is the first known analysis of the bidirectional relationship between rSST and 24-h behaviors. The negative association between rSST and other-SED suggests that rSST may displace rather than contribute to more cumulative sedentary time. These findings advocate that contexts of sedentary behavior should be considered as distinct behavioral targets in intervention development. Future interventions targeting rSST reduction should also include strategies to reduce total sedentary time.

NCT04464993.