Stress and sleep in nurses employed in 3 x 8 and 2 x 12 fast rotating shift schedules

We compared two 3 x 8 shift rotas with backward rotation and quick return (morning and night shift in the same day) in a 5- or 6-day shift cycle, and a 2 x 12 shift rota with forward rotation in a 5-d shift cycle. A total of 294 nurses (72.6% women, mean age 33.8) were examined in a survey on work-related stress, including the Standard Shiftwork Index. Ten nurses per each shift roster recorded their activity and rest periods by actigraphy, rated sleepiness and sleep quality, and collected salivary cortisol throughout the whole shift cycle. Nurses engaged in the 2 x 12 rota showed lower levels of sleep disturbances and, according to actigraphy, sleep duration was more balanced and less fragmented than in the 3 x 8 rosters. The counter-clockwise shift rotation and quick return of 3 x 8 schedules reduce possibility of sleep and recovery. The insertion of a morning shift before the day with quick return increases night sleep by about 1 h. Nurses who take a nap during the night shift require 40% less sleep in the morning after. The 2 x 12 clockwise roster, in spite of 50% increased length of shift, allows a better recovery and more satisfying leisure times, thanks to longer intervals between work periods. Sleepiness increased more during the night than day shifts in all rosters, but without significant difference between 8-h and 12-h rosters. However, the significantly higher level at the start of the night shift in the 3 x 8'' rotas points out that the fast backward rotation with quick return puts the subjects in less efficient operational conditions. Some personal characteristics, such as morningness, lability to overcome drowsiness, flexibility of sleeping habits and age were significantly associated to sleep disturbances in nurses engaged in the 3 x 8'' rotas, but not in the 2 x 12'' schedule.