Night time noise is known to disturb sleep, however the effects of occupational noise during the daytime are currently unknown. A recent article in the Sleep Medicine journal “Will daytime occupational noise exposures induce night time sleep disturbance” examined personal noise exposure during the day on documented sleep characteristics. 48 participants who had been employed for at least six months were randomly designated to be assessed on high- and low-noise workdays for 8 hours. After the work day, sleep studies, audiometry testing, autonomic nervous system (ANS) function tests and serum cortisol tests were conducted.Participants with higher personal noise exposure during the day were found to have a lower percentage of slow wave sleep (one of the deep sleep stages) and lower sleep efficiency. In addition, after work, personal noise exposure was revealed to be related to increased serum cortisol levels, sympathetic activity and blood pressure – all markers of stress. It was concluded that daytime occupational noise exposure had sustained effects on night time sleep quality, specifically on slow wave sleep and sleep efficiency. These disturbances could be partially explained by post-shift elevated cortisol and ANS activity. Put simply, noise exposure during the work day may cause physical stress and may make you sleep less well.