question: BACKGROUND AND OBJECTIVE: During the first corona wave public life largely came to a standstill. Many employees started to work from home to protect themselves from infection. The purpose of this study was to investigate changes in sleep behavior and daytime sleepiness when people changed from working in the office to mobile working from home. METHOD: Office workers were asked about their chronotype, their usual sleep routine and the occurrence of daytime sleepiness on office workdays and during mobile working. Data collection took place between 15 July 2020 and 7 August 2020. An anonymized online survey tool was used. The composite scale of morningness (CSM) in the German language version was used to determine the chronotype. The association of age, gender, chronotype, sleep quality and sleep duration with self-rated daytime sleepiness was examined using multivariable logistic regression analyses. RESULTS: The data of n = 228 individuals could be analyzed. Sleep duration increased while working from home. The proportion of persons with less than 7.5 h time in bed decreased from 56.6% to 33.4% and the proportion of those with more than 8 h time in bed increased from 43.4% on office workdays to 66.6% when working from home. The percentage of people who always or often felt sleepy at work decreased from 47% on office workdays to 15% when working from home. The chronotype showed a significant association with daytime sleepiness on office workdays but not when working from home. DISCUSSION: The reduction of daytime sleepiness could be explained by longer sleep duration and higher satisfaction with sleep quality. Late chronotypes seem to benefit particularly when working from home. A flexible start of work, the consideration of the chronotype and measures for health-promoting sleep could reduce daytime sleepiness and thus improve occupational safety and health.