A sedentary lifestyle and thus increased daily sedentary time has become a global health problem increasing the risk of non-communicable diseases, NCDs. NCDs are increasing of course for other reasons too, such as dietary habits but daily sedentary time is highly changeable behaviour, and might be even easier to change than dietary habits. How many sedentary hours per 24 h is too much? Figures vary depending on the target population.
Very young children (infants and toddlers under 5 years old) have shown associations between higher screen time, especially evening screen time, and shorter total sleeping time and other sleeping-related outcomes [Citation1]. Reaching sleeping time (about 10 h per night) and screen time (<2 h) recommendations in children and adolescents (6–20 years old) was associated with better mental health compared to only meeting physical activity recommendations [Citation2]. In adolescents (10–15 years old, with a mean total daily sedentary time of 6.75 h) those with higher screen time reported lower health-related quality of life [Citation3].
Regarding the adult population, a meta-analysis showed that both 5-6 h of screen time and 11 h of total sedentary time were in the same way related to a higher risk of cardiovascular ill-health [Citation4]. Further, independently of physical activity level high daily sedentary time seems to increase the risk of several cancer types. Also, often are persons with high daily sedentary time fighting with overweight. Obesity in turn is related to many cancer types [Citation5]. In older persons high daily sedentary time (>7.5 h) was associated with knee and hip pain in men and hip pain in women [Citation6].
Many of the studies in above mentioned systematic reviews are of poor quality, thus we need more research on the topic of sedentary time and its health consequences. We do know that high sedentary time increases the risk for many health conditions. But we do not know enough about how to support the change, with what and where to relocate the time spent sedentary. Research is also needed on how to motivate to decrease sedentary time and the length of sedentary bouts. The motivational aspects are not necessarily the same as when motivating to increase physical activity level. There is an emerging need for high-quality intervention studies to change this global risk behaviour.
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References
- Janssen X, Martin A, Hughes AR, et al. Associations of screen time, sedentary time and physical activity with sleep in under 5s: a systematic review and meta-analysis. Sleep Med Rev. 2020;49:101226. doi: 10.1016/j.smrv.2019.101226.
- Sampasa-Kanyinga H, Colman I, Goldfield GS, et al. Combinations of physical activity, sedentary time, and sleep duration and their associations with depressive symptoms and other mental health problems in children and adolescents: a systematic review. Int J Behav Nutr Phys Act. 2020;17(1):72. doi: 10.1186/s12966-020-00976-x.
- Lucena JMS, Loch MR, Silva E, et al. Sedentary behavior and health-related quality of life in adolescents. Cien Saude Colet. 2022;27(6):2143–2152. doi: 10.1590/1413-81232022276.11842021.
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- Kang SH, Joo JH, Park EC, et al. Effect of sedentary time on the risk of orthopaedic problems in people aged 50 years and older. J Nutr Health Aging. 2020;24(8):839–845. doi: 10.1007/s12603-020-1391-7.