Percentage of workers reporting depression and insufficient sleep divided according to self-reported natural light exposure groups for Equatorial and Arctic groups.

<p>Percentage of workers reporting depression and insufficient sleep divided according to self-reported natural light exposure groups for Equatorial and Arctic groups.</p

Natural light exposure (hours/4-week cycle) of groups of workers according to light exposure.

<p>^a Alternating morning/afternoon shifts</p><p>^b Alternating morning/afternoon/night shifts</p><p>^c Starting time before 06:00 h</p><p>^d Starting time after 06:00 h</p><p>^e Weighted averages according to the number of work days and number of days-off</p><p>* Difference mean between work days and days-off within group, P<0.01</p><p>Natural light exposure (hours/4-week cycle) of groups of workers according to light exposure.</p