A study published in the January 21 issue of the Proceedings of the National Academy of Sciences shows that disrupted sleep rhythms can cause “severe damage” to more than 1,000 genes, which could explain why regular night shifts and jet lag can lead to a range of health problems. The study was conducted by researchers including Professor Derk-Jan Dijk of the University of Surrey in the UK. They delayed the sleep-wake cycle of 22 subjects by four hours by adjusting the brightness of the room light. After three days, the sleep of these subjects appeared in the middle of the day, and the sleep and waking hours were reversed day and night, but the total sleep time was not reduced. The researchers collected blood samples from the subjects to observe changes in their circadian rhythms of gene expression. The results showed that before the study began, the expression of about 1,400 genes in the body showed circadian rhythms, but at the end of the experiment, the number was about 230. This suggests that many biological processes in the human body are widely affected. According to Decker, “This study may help us understand the adverse health consequences associated with night shifts, jet lag disorders, and other situations that disrupt circadian rhythms in gene expression.” Decker said the effects of disrupted sleep on the body may be similar to those of aging.