Our hair holds a secret about our sleeping patterns. A recent study has found that our hair follicle cells record our waking and sleeping cycles. It used to be thought that the brain controlled these circadian rhythms but approximately 10 years ago, clock genes were discovered as the real determiners of our body’s internal clocks.
This study lead by Makoto Akashi of Yamaguchi University in Japan, enabled researchers to devise a way to monitor our circadian rhythms using hairs plucked from our head or chin. Previously, the only method known to accurately test these clock gene cycles was from a blood sample or skin biopsy. Circadian clock activity was measured in the hair follicle cells by testing proteins from RNA, our cell’s holder of genetic instructions, located in the bulb of the hair.
The researchers tested two groups. First they asked volunteers to sleep later and later over a period of three weeks. Each day when the volunteers woke, they were instructed to shine a bright light on themselves for 30 minutes to mimic light coming from the sun. After three weeks, the volunteers were waking four hours later than the time they had started. When their hair was tested, it showed a lag of one and a half hours indicating that their bodies were changing their internal clocks but still were behind similar to experiencing jet lag.
Next, they decided to test real shift workers who rotated between day shift (6 am to 3pm) one week and afternoon shift (3pm to 12mn) the next week followed by a return to day shift. Their clock gene activity lagged five hours behind, only shifting three hours indicating that the shift workers needed more than one week to change their internal clocks that many hours.
Research about circadian rhythms and developing simple ways measure them is important in understanding what happens to the body after jet lag and in similar conditions. Shift workers struggle constantly with shifting circadian clocks, which is thought to contribute to increased risk of heart attacks or stroke.