The Influence of Break Timing on the Sleep Quantity and Quality of Fly-in, Fly-out Shiftworkers

Although shift and break timing is known to affect the sleep of shiftworkers, this hasnot been demonstrated in Fly-in, Fly-out (FIFO) settings which, compared to residentialbased settings, may be favourable for sleep. This study investigated the sleep quantityand quality of shiftworkers working a FIFO operation comprising of shifts, and thereforebreaks, across the 24-h day. The sleep of 24 males (50.43 ± 8.57 yr) was measured usingactigraphy and sleep diaries. Morning breaks were associated with less sleep (09:00–12:00h; 4.4 ± 1.3 h) and a poorer sleep quality (06:00–09:00 h; 3.1 ± 1.0, “average”) comparedto breaks beginning between 00:00 h and 03:00 h (6.8 ± 1.7 h; 2.2 ± 0.9, “good”). Sleepefficiency remained constant regardless of break timing (85.9 ± 5.0% to 89.9 ± 3.5%).Results indicate that even in operations such as FIFO where sleeping conditions arenear-optimal and the break duration is held constant, the influence of the endogenouscircadian pacemaker on sleep duration is evident.