Sleep Hormone Serotonin Found to be Lower in Rotating Shift Workers

It is well known that rotating shift workers have a hard time getting enough sleep, and a new study helps to explain why. The findings will be useful to ergonomists and other professionals who design shift patterns to lessen the ill effects of disrupting the natural sleep cycle. These are well known, and include a higher risk of illness and accidents and impaired performance.

Led by Carlos J. Pirola, Ph.D., a team at the Universidad de Buenos Aires in Argentina compared 437 male day workers with 246 rotating shift male workers. They found the day workers’ serotonin levels were significantly higher than the shift workers’ levels. Serotonin is a hormone and neurotransmitter in the central nervous system believed to play an important role in the regulation of sleep. The research was published in the August issue of the journal Sleep.

The researchers say the findings “may be important for targeting effective therapeutic strategies to ameliorate the associated comorbidities and behavioral problems in rotating shift workers.” The term “comorbidities” refers to the coexistence of two or more disease processes.

The researchers also noted that many of the ill effects of the rotating shift pattern have long been associated with disruption of the circadian rhythm, the natural 24-hour cycle that prompts the body to stay awake when it is light and sleep when it is dark. Shifts often put workers on the opposite cycle, which almost guarantees sleep difficulties.

Study after study links sleep deprivation with poor judgment and performance on the job. In June 2006 Ergonomics Today™ reported research in Japan that quantified some of the ill effects. It surveyed 3,075 employees of a chemical company in Osaka. Factoring in salary levels, researchers questioned the employees’ sleeping habits and alertness over a one month period during work hours or while driving. The results showed the workers were sleep deprived and that their efficiency was reduced by as much as 40 percent. This led to frequent accidents, lateness and absenteeism that cost Japan 3.5 trillion yen (US $30.7 billion) a year, mainly in lost productivity.

Sources: Sleep; Ergonomics Today™