Genetics, Medical News, Sleep

Genetically-predisposed ‘morning people’ adjust to daylight savings time faster

The so-called “early birds,” who are normally early risers in the morning, acclimated to the hour advance of daylight savings within a few days, according to the study. It took almost a week for those who were not early risers to acclimatize.

Daylight Savings Time (DST),  the practice of people advancing their clocks so that darkness arrives at a later hour, has been known to have a negative effect on both the individual, as well as society as a whole. Recently, University of Michigan researchers have found that early birds are capable of adjusting to DST much more efficiently than night owls. 

The way an individual feels, as well as many physiological activities that occur in a day are controlled by a person’s circadian clock. Circadian clocks, as explained below, refers to a human’s personal cycle which transitions daily from feelings of alertness to tiredness. These circadian clocks become misaligned, and take multiple days to reset, when individuals go through a sudden external change, such as jet lag. This misalignment has been linked to a wide range of physical and mental health issues. Unfortunately, little data exists pertaining to how genetic diversity influences the effects of these abrupt external changes.

Neuroscientist and senior author of the experiment Margit Burmeister, Ph.D., stated “It’s already known that DST has effects on rates of heart attacks, motor vehicle accidents, and other incidents, but what we know about these impacts mostly comes from looking for associations in large data pools after the fact.” 

She then continued, “These data from direct monitoring and genetic testing allows us to directly see the effect, and to see the differences between people with different circadian rhythm tendencies that are influenced by both genes and environment. To put it plainly, DST makes everything worse for no good reason.”

The circadian clock is a major contributor to the way the human body functions. Human functions such as hormone release, body temperature, metabolism, and sleep/wake patterns, are managed according to circadian clocks. The light-dark cycle of day and night is responsible for controlling these clocks. The human circadian clock synchronizes itself with the lighting of day and night. 

The research draws on data from 831 doctors who were in their first year of post-medical school training when Daylight Savings occured in the Spring of 2019. Through genetic research, the study focused mainly on 260 of these doctors, separating them into two groups: early risers and night owls. Researchers then studied their sleep patterns one week prior to and one week following the time shift resulting from Daylight Savings. 

In the study, the so-called “early birds”, who naturally are earlier risers in the morning, adjusted to the hour advance of daylight savings within a few days. Those who are not considered early birds, took over a week to adjust. 

With the finding of the major differing effects that DST have on different individuals, this study stresses the fact that genetic variation may play a big part in mitigating bigger shifts. The study aids in providing a better understanding of how people react to shift work-induced chronic misalignment, and the extent of the health problems it can bring to many.

“This study is a demonstration of how much we vary in our response to even relatively minor challenges to our daily routines, like DST. Discovering the mechanisms underlying this variation can help us understand our individual strengths and vulnerabilities better,” says Srijan Sen, M.D., Ph.D., coauthor of the study. 


The study was published in Scientific Reports, on July 20th, 2021.

Tyler, J., Fang, Y., Goldstein, C. et al. Genomic heterogeneity affects the response to Daylight Saving Time. Sci Rep 11, 14792 (2021). https://doi.org/10.1038/s41598-021-94459-z

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