Irregular sleep patterns throw off the body's internal clock, even after just one night without sleep. Photo by ile404/Shutterstock
WASHINGTON, July 21 (UPI) -- Irregular sleep patterns, including just one night of no sleep, can alter metabolism, cell function and, in women, speed up the development of breast cancer if they are predisposed to it, according to two new studies.
Researchers in both studies said the disruption of the body's internal clock throws off cell function.
One night without sleep causes alterations to the way that genes are expressed in the body, according to a study published in the Journal of Clinical Endocrinology and Metabolism.
Previous studies have shown sleep loss affects metabolism, said Uppsalla University researcher Jonathan Cedernaes, in a press release, and as a result, sleep loss is linked to obesity and type 2 diabetes. This led researchers to recruit 15 healthy men who were either kept awake or permitted to sleep during two overnight sessions in the lab.
Blood samples taken before and after each of the sessions, as well as small tissue samples taken from the thigh and stomach after participants either did or did not sleep, showed that the regulation and activity of "clock genes" was altered after a single night of not sleeping.
Cedernaes said it was interesting the genes could be altered so quickly, and that it would happen to such important genes. He also said that, while the changes started over one night, how long they last is unclear.
"It could be that these changes are reset after one or several nights of good sleep," Cedernaes said. "This could mean that at least some types of sleep loss or extended wakefulness, as in shift work, could lead to changes in the genome of your tissues that can affect your metabolism for longer periods."
Researchers in another study published in Current Biology said mice prone to developing breast cancer normally have tumors after 50 weeks, but those whose body clocks were delayed by 12 hours every week for a year were 20 percent heavier and developed breast cancer 8 weeks earlier. Interpreting the data from the study for humans, they said at-risk women with poor sleep patterns could be diagnosed with breast cancer as much as 5 years earlier.
"The general public health message coming out of my area of work," Dr. Michael Hastings, of the United Kingdom's Medical Research Council, told the BBC, "is shift work, particularly rotational shift work, is a stress and therefore it has consequences."