London - Working night shifts throws the body into chaos and may cause long-term damage, scientists say.
They have found that a topsy-turvy sleep cycle causes havoc deep inside our DNA.
This could help explain everything from why jet lag makes us feel so lousy to why shift work is linked to a host of health problems from obesity to diabetes.
The researchers from Surrey University delayed the bedtime of 22 healthy men and women by four hours a day for three days, until they were going to sleep when they would normally wake up and vice versa. Blood tests showed that when sleeping normally, rhythmic genes, which make up six percent of the total, were timed to be more or less active at certain times of the day.
For instance, some genes involved in defending the body against disease worked harder during the day than at night.
But when on a night-shift pattern, sleeping during the day and staying awake at night, this rhythm was “profoundly disrupted”. Researcher Dr Simon Archer told the BBC: “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.”
Fellow researcher Professor Derk-Jan Dijk described the effect as “chaos”. He added: “This research may help us understand the negative effects associated with shift work, jet lag and other conditions in which the rhythms of our genes are disrupted.”
Other experts said it was surprising that such a big effect had occurred after only a few weeks of disrupted sleep. They said that, long-term, the genetic chaos could lead to many health problems.
The findings, detailed in the journal Proceedings of the National Academy of Sciences, could shed light on jet lag, ageing and other processes in which the body clock is altered. Shift work has previously been linked to breast cancer and the World Health Organisation ranks night-working one rung below asbestos and smoking when rating potential triggers of cancer.
Dr Peter Carter, general secretary of the Royal College of Nursing, said it was critical the health of shift workers was not ignored. - Daily Mail