SLEEPINESS AND DAYS OF RECOVERY

The speed of recovery after a week of work is apparently assumed to be one or two days, since custom and legislation in most countries prescribes two days off after five days of work. However, there is little scientific support for this notion. Further, the situation for those working irregular work hours may be quite different because of night work, long shifts, or long sequences of working days. This paper brings together data from a series of studies, conducted by the authors, with the specific purpose of looking at the recovery process, particularly when irregular work hours are involved. The results show that for the worker working an average normal office week, two days of recovery are normally sufficient. For those who work long shifts in long sequences, three days are needed for normalization, whereas twelve hour shifts in two or three day sequences seem no to cause accumulated fatigue. Interestingly, fatigue/sleepiness is often at its peak during the first day of recovery, not the last day of the working week. Air crews and oilrig workers take a longer time to recover, probably because of a need to adjust their biological clocks. As a rule, long haul air crews are usually more fatigued than short haul crews during their days off, despite the fact that long haul flying is voluntary and opted for by those who fly. Also, train drivers are affected during their days off by their irregular work hours, in particular backwards rotating schedules seem to cause accumulation of fatigue. The results suggest that one day of recovery is never sufficient, two days are usually sufficient, whereas three to four days are necessary after periods of severely disturbed circadian rhythmicity