This weekend is officially the end of summer. Today, we turned our clocks back an hour – known as “falling back” as opposed to “springing forward” – to signal the end of daylight savings.

During this time shift, while we’re ready to relish the extra hour’s sleep and more light on our way to work we’re not so excited about being plunged into darkness earlier in the evening. But if you thought that was the extent of the impact of changing the clock, think again. It turns out, changing the time has some pretty noticeable physical effects – good, bad and unexpected.

Men get cluster headaches

According to Everyday Health, a study by a headache pain specialist at Cleveland Clinic suggests that cluster headaches (ones that usually occur daily for a 6-8 week duration before disappearing) can be triggered with a change to time.

The phenomenon is said to occur more likely in men than women, typically starting a few days after winding the clocks.

Your circadian rhythm goes back to normal

Any time change will affect sleep schedules. However, some research suggests that because our internal sleep schedule or circadian rhythm tends to sync with the sun, springing the clocks forward during the start of daylight savings actually throws a major spanner in the works that the body never quite adjusts to. Rather, once daylight savings ends, our internal sleep schedules go back to suiting the sun (sleeping when it’s dark, waking when it’s light), returning them back to normal.

According to research by Current Biology, “When you change clocks to daylight saving time, you don’t change anything related to sun time,” lead researcher Till Roenneberg of Ludwig-Maximilians-University in Munich told ABC News.

“This is one of those human arrogances – that we can do whatever we want as long as we are disciplined. We forget that there is a biological clock that is as old as living organisms, a clock that cannot be fooled. The pure social change of time cannot fool the clock.”

Depression can be triggered

Little good can come from losing an hour of afternoon sunshine. So much so that a Danish study saw fit to put the theory to the test.

During the experiment, the rate of depression diagnoses was higher than expected in the month after Fall Back.

“We are relatively certain that it is the transition from daylight saving time to standard time that causes the increase in the number of depression diagnoses and not, for example, the change in the length of the day or bad weather. In fact, we take these phenomena into account in our analyses,” co-author Søren D. Østergaard, MD, associate professor of clinical medicine at Aarhus University in Denmark, said in a press release.