Our Internal Clocks Are At Odds With Daylight Saving Time

Our bodies are very used to day-night cycles, but Daylight Saving Time can disrupt when they think the day starts and ends.

Our Internal Clocks Are At Odds With Daylight Saving Time
Getty Images / Joe Raedle

When we adjust our clocks for Daylight Saving Time, our bodies react by shifting our circadian rhythms to try and align with the new schedule. But when this change happens quickly and involuntarily, it can throw off our natural clocks and result in health problems.

Our bodies are hardwired to react in certain ways based on the appearance and disappearance of daylight, and sudden changes to that cycle don't go over well. For instance, when it gets dark outside, our eyes send a signal to the part of the brain that controls our internal clock, sending a cue that it's time to go to sleep. Our brains relay that message to the body so it releases melatonin, a hormone that helps us sleep.

A clock is set back by an hour for daylight saving time

European Union Might Abolish Daylight Saving Time

More than 80% of people surveyed were in favor of the change.


But when we change our clocks, our circadian rhythms still operate as if the change never happened. Researchers say nearly no one following Daylight Saving Time can get their body's clock to align with the current time before it falls back to standard time in November.

And these disruptions have implications for our health. Studies show that when our circadian rhythms are thrown off, it increases the risk of having a heart attack or developing cancer, and can lead to mood swings or poor cognitive functioning.