Jet lag or working the night shift may take a toll on your health. Feelings of fatigue, nausea, and anxiety to stomach pains and memory problems are common ailments experienced by travelers and shift workers, although the cause has remained unclear. According to a recent study, jet lag and the night shift’s disruption of the 24-hour biological clock, damage genetic rhythm while increasing the risk of cancer, heart disease, and diabetes.
Jet lag is nearly unavoidable for travelers with approximately 93 percent experiencing its effects at some point, says the American Sleep Association. It may take the body one day per time zone crossed to recover and slowly adjust to the time changes. Similar to travelers, shift workers could possibly suffer from sleep disorders and may be more susceptible to developing a series of diseases and mental disorders due to a shift in the body clock. A team of researchers at Surrey University in the UK, believe jet lag and night shift work disrupts the body’s biological clock, damaging more than 1,000 genes that are responsible for maintain, repairing, and protecting the body.
The study, published in the journal Proceedings of the National Academy of Sciences, examined the effects staying in a controlled environment without a natural light-dark cycle had on a small cohort in a 28-hour day pattern. Twenty-two men and women aged 22 to 29 — none who suffer from sleep deprivation — were recruited by the researchers to tease apart the effects of the body clock and the effects of sleep. The participants’ blood was drawn prior to the study and during the study as a way to observe what was happening to the rhythms of gene expression under this shifted sleep-wake pattern.
The findings revealed the activity of 1,396 genes rose and fell in line with a healthy circadian rhythm prior to the study, but only 40 or so kept their rhythms after the study. Another 180 genes — who normally have constant levels of expression — began to rise and fall instead. "Over 97 percent of rhythmic genes become out of sync with mistimed sleep, and this really explains why we feel so bad during jet lag or if we have to work irregular shifts,” said Dr. Simon Archer, co-author of the study and reader in Chronobiology at Surrey, Medical News Today reported. These included genes involved with transcription and translation — the transcriptome — which interpret the DNA code for making proteins and controlling cell behavior.
The researchers were surprised to find jet lag and nightshift work had a similar effect on gene activity to aging. The daily rise and fall of gene expression becomes less definite as people age, which was also observed when people experienced mistimed sleep in the study. “…We lose the strength of the signal, as it were, and we know that is also lost in ageing,” said Archer, The Guardian reported.
The damage of these genes could help provide an explanation as to why working a night shift has been classed as a “probable human carcinogen.” In a study published in the journal BMJ, Canadian researchers found long-term night shift working is linked to the raised risk of breast cancer in women. Women who worked nights for 30 or more years were twice as likely to have developed the disease, after the researchers took into account potentially influential factors. This finding suggests that sleep disturbances, disrupted body rhythms, vitamin D, or lifestyle differences, may attribute to the occurrence of breast cancer in night shift workers.
Similarly, a study published in the Journal of Biological Rhythms, researchers found people who regularly work the night shifts are twice as likely to have diabetes, even if they have retired and have a daytime schedule. Body mass index and diabetes rates were higher in night shift retirees compared to former daytime workers. This finding suggests that night shift workers should adopt behavioral strategies regarding diet, exercise, and body clock adjustment. These workers are a high risk for metabolic and cardiac diseases, says the Beth Israel Deaconess Medical Center.
These studies will have an impact that goes beyond jet lag and shift work. Genetic rhythm disruption could even affect how medicines work. John Hogenesch, an expert on the effects of circadian clocks on physiology at the University of Pennsylvania told The Guardian, “Many common drugs work properly only if they are taken at the right time.” The cholesterol-cutting statin, Mevacor, is said to work best at night because levels of the enzyme it targets are highest at that time.
Patients who are in intensive care are more likely to experience the effects due to their unnatural environment. This setting causes their body clocks to be out of sync with their environment and can become problematic when it comes to taking certain drugs at the right time. Further research may help doctors determine when’s the best “time” to give medicine to these patients to maximize the drug’s full effects.
Although the authors of the recent study are uncertain whether the effects they observe have direct clinical consequences, they do believe there should be further investigation. The disruption of more than 1,000 genes during jet lag or night shift work in just three days can lead to serious health issues that may be prevented with future studies.
Archer SN, Bucca G, Dijk DJ, Kabiljo R, Laing EE, Lzaar AS et al. Mistimed sleep disrupts circadian regulation of the human transcriptome. PNAS. 2013.
Aronson K, Burstyn I, Grundy A, Lai AS, Lee D, Lohrisch C et al. Increased risk of breast cancer associated with long-term shift work in Canada. BMJ. 2013.
Buysse DJ and Monk TH. Exposure to Shift Work as a Risk Factor for Diabetes. Journal of Biological Rhythms. 2013.