Japanese researchers have just resolved a scientific conondrum: how to measure peripheral clock gene expression in living humans and alterations in clock gene expression with lifestyle changes without invasively and routinely sampling heart, lung, or liver tissue? The hair follicle! We already know that the hair follicle is the active ingredient in Polyjuice Potion used to transform into its donor for a few hours, but the use of hair follicles in this study is equally as innovative.

In this study, human subjects were asked to keep a routine bed/risetime schedule which was verified through actigraphs. Actigraphs are watches that sleep study subjects commonly wear during the course of a study to measure their day and night time activity. It is also an easy way for the sleep researchers to ensure subject ResearchBlogging.orgcompliance to the mandatory bed/risetimes. In this study, a hair follicle was taken every 3 hr over a period of 48 hr to characterize the circadian expression of clock genes which regulate the endogenous (circadian) rhythm in the SCN. As shown below, four subjects activity records nicely complement circadian expression of clock genes.

What happens if you advance bed and risetimes, however? You see a shift in the circadian expression of clock genes too!!! This was accomplished by having the subject go to bed an hour earlier every day for 5 days.

And what would these circadian gene expression profiles look like in a rotating shift worker? That is, someone who every week has to drastically change their bed and risetime schedule and lifestyle from going to bed at 10PM and waking up at 6 AM to going to bed at 4 AM and waking up at 1 PM? Here, circadian gene expression appears to not be shifted as much as it is attenuated within only three weeks!!!

This attenuation of rhythmic gene expression, which you may know from my research and others, can actually increase predispositions to drug abuse and psychiatric disorders. Individuals with single nucleotide polymorphisms of PER and CLOCK genes, which also attenuate rhythmic clock gene expression, have high reports of alcohol use and depression. Alcohol use is already high among shift workers, because many of them use it to fall asleep in order to alleviate insomnia associated with shift work. A combination of shift work and a history of alcohol use for mitigating work-related sleep disturbance may be the tipping point of full-blown alcoholism.

I hate to not end this post so morbidly, so let me mention how this research will benefit public health. By knowing the preferred circadian phase of an individual, that is, whether their body operates as a lark, owl, or neither, employers may be able to better assign work shifts that will guarantee more productivity, less on-the-job accidents, improve company morale, and possibly, curb a work-induced downward spiral of alcoholism. This is, of course, the scientist speculating about the world as she sees it through her rosy-colored glasses……
Akashi M, Soma H, Yamamoto T, Tsugitomi A, Yamashita S, Yamamoto T, Nishida E, Yasuda A, Liao JK, & Node K (2010). Noninvasive method for assessing the human circadian clock using hair follicle cells. Proceedings of the National Academy of Sciences of the United States of America PMID: 20798039