The Influence Of A Sit-stand Desk On Sleepiness, Physical Discomfort, Physical Fatigue And Mental Fatigue

Sleepiness, pain and fatigue significantly impact the productivity of office workers, and prolonged sitting may negatively impact these feelings during deskwork. Using a sit-stand desk could benefit these measures, but it is not clear. PURPOSE: To examine whether using a sit-stand desk to alternate posture could improve ratings of sleepiness, mental fatigue, physical fatigue and physical discomfort. METHODS: 25 inactive adults (age: 42 ± 12 yr; BMI: 31.9 ± 5.0 kg/m2) participated in a randomized cross-over study of two simulated 8-hr workdays (with a lunchbreak) while performing continuous sitting (SIT) or alternating sit-stand postures every 30 min (SIT-STAND). Ratings of sleepiness were measured by the 9-pt Karolinska Sleepiness Scale each hr while at the desk. A validated questionnaire measured the overall presence of physical discomfort, degree of physical discomfort (averaged across 10 body locations) and degree of physical and mental fatigue every 2 hr by 100-pt visual analog scales. Outcomes were checked for skewness and log transformed. Generalized linear mixed models, controlling for baseline values, evaluated differences across condition and time. RESULTS: Sleepiness increased across the day (p<0.001) and was lower in SIT-STAND vs. SIT (p=0.036). Mental fatigue was similar across time (p=0.095) and conditions (p=0.068). Comparing SIT-STAND to SIT, the presence of any physical discomfort was less frequently reported (p=0.006) and degree of physical discomfort was lower (p<0.001). The presence or degree of physical discomfort did not differ over time (p=0.378 and p=0.089, respectively). Physical fatigue was similar across the day (p=0.050) and conditions (p=0.712). (See table 1) CONCLUSION: Using a sit-stand desk during daily work activity resulted in better ratings of sleepiness and physical discomfort compared to sitting all workday. These measures are important for presenteeism of office workers and should be explored over a longer duration.