Shift start times can impact sleep, alertness: study

Regulations limiting the number of hours employees work also should address shift start times, suggests research from Washington State University Spokane.

A study using mathematical modeling to predict fatigue among workers found shifts beginning between 8 p.m. and midnight yielded poorer performance and less-than-adequate sleep per 24 hours, according to a press release from the Westchester, IL-based American Academy of Sleep Medicine. Shifts that started between 9 a.m. and 2 p.m. allowed for the most estimated sleep.

Likewise, the study predicted minimum on-the-job fatigue for shifts starting at 9 a.m. and maximum fatigue for shifts beginning after 11 p.m. However, estimated fatigue was lower for shifts starting after midnight than shifts starting just before midnight. Researchers said this indicates that circadian rhythms might allow employees who work night shifts that start after midnight to get more sleep than those who begin their shifts between 8 p.m. and midnight.

The study was presented June 8 at SLEEP 2010, the 24th annual meeting of the Associated Professional Sleep Societies LLC.