Every spring, most states in the United States move their clocks forward by one hour to begin daylight saving time. The idea behind this shift is to extend evening daylight and reduce energy use.
However, many health experts have long suspected that changing the clock can disturb the body’s natural sleep cycle. A new study led by researchers at the University of California, Davis now provides evidence that this small time shift may have real effects on people who suffer from migraines.
The study was led by neurologist and sleep specialist Dr. Sasikanth Gorantla and was published in the Journal of Clinical Sleep Medicine. The research explored how the transition from standard time to daylight saving time affects adults who already experience migraines.
The findings suggest that even a one‑hour change in the clock can disrupt the body’s internal timing system and may lead to more migraine attacks and less deep sleep.
Migraines are a neurological condition that affects more than 35 million people in the United States. Around the world, migraines are considered one of the leading causes of disability.
The condition occurs more often in women than in men and can seriously interfere with daily life. Migraine attacks often involve severe head pain along with other symptoms such as nausea, vomiting, and strong sensitivity to light, sound, or smells.
Many people with migraines also have very sensitive brains when it comes to changes in routine. Small disruptions in sleep patterns, travel across time zones, stress, or hormonal changes can trigger migraine attacks.
Because daylight saving time changes the body’s sleep schedule suddenly, researchers wanted to understand whether the shift could trigger more migraines.
To investigate this question, the UC Davis research team followed a group of adults who had episodic migraines. The study included 23 participants, consisting of 22 women and one man. All participants were observed for four weeks surrounding the spring daylight saving time change that occurred on March 12, 2023.
For two weeks before the time change and two weeks after it, participants carefully recorded their headaches and migraine symptoms in daily diaries. They also used special sleep sensors placed under their mattresses.
These sensors measured sleep architecture, which refers to the different stages of sleep that occur during the night, including light sleep, deep sleep, and rapid eye movement sleep.
The researchers defined migraine days using clear medical criteria. A migraine was counted if the headache included at least two key features such as pain on one side of the head, a pulsating or throbbing feeling, moderate to severe pain intensity, or pain that worsened with physical activity.
Other symptoms such as nausea, vomiting, and sensitivity to light or sound were also considered signs of migraine attacks.
Headaches that did not meet these criteria were recorded separately as non‑migraine headaches. These headaches are usually milder and often described as dull or aching rather than severe and pulsating.
The researchers also considered other factors that can influence migraines. For example, migraines triggered by hormonal changes during the menstrual cycle were excluded from the analysis. This helped ensure that the results focused mainly on the effects of the clock change rather than other known triggers.
After analyzing the data, the researchers found that the shift to daylight saving time had a clear effect. The number of migraine days increased significantly after the clock moved forward. Before the time change, the rate of migraine days was about 7.76 per 100 person‑days of observation.
After the clock change, this number rose to 13.35 migraine days per 100 person‑days. In other words, migraine frequency almost doubled.
Interestingly, the severity of the migraines did not change much. Participants reported similar pain intensity levels before and after the clock transition. However, their sleep patterns did show a noticeable change.
One of the most important findings was a reduction in deep sleep. Deep sleep is a stage of sleep that is especially important for physical recovery and brain health. During deep sleep, the brain clears waste products and restores important biological functions.
In the study, participants averaged about 94 minutes of deep sleep per night before the time change. After daylight saving time began, this dropped to around 84 minutes.
Although deep sleep decreased, the total amount of sleep participants received each night remained roughly the same. This suggests that the time change did not necessarily shorten sleep overall, but it did affect the quality and structure of sleep.
Dr. Gorantla explained that the results highlight how sensitive the body’s internal clock can be. The circadian rhythm, which regulates sleep and wake cycles, relies on consistent timing cues such as light exposure and regular sleep schedules. When the clock shifts suddenly, the body may struggle to adjust quickly.
The findings also support growing concerns among sleep researchers about the health effects of daylight saving time. Previous studies have linked clock changes to higher risks of heart attacks, workplace injuries, and car accidents in the days following the shift. This new research suggests that migraines may be another health issue affected by the change.
The study also offers lessons for other situations that disrupt circadian rhythms. Jet lag from traveling across time zones and irregular sleep schedules from shift work may cause similar disruptions. In people who already have sensitive neurological systems, these disturbances may increase the likelihood of migraine attacks.
To help reduce the effects of daylight saving time changes, the researchers recommend several practical strategies. Maintaining good sleep habits is one of the most important steps.
Going to bed and waking up at the same time each day can help stabilize the body’s internal clock. Gradually adjusting sleep schedules before the time change may also make the transition easier.
Morning sunlight exposure is another helpful tool because natural light helps synchronize the body’s circadian rhythm with the day‑night cycle. Reducing bright light in the evening can also support healthy sleep timing.
Regular exercise, staying hydrated, and avoiding known migraine triggers such as alcohol and excessive stress may further reduce the risk of attacks.
When reviewing the findings overall, the study highlights how even small environmental changes can influence brain health. A one‑hour shift in time may seem minor, but for people with migraine disorders it can disrupt sleep patterns and increase the likelihood of headaches.
The research suggests that maintaining circadian stability is an important part of managing migraines.
However, the study also has limitations. The number of participants was relatively small, and most were women, which means larger studies will be needed to confirm the results. In addition, the research focused only on the spring transition to daylight saving time, so future work may examine the effects of the fall clock change as well.
Despite these limitations, the results add to a growing body of evidence suggesting that daylight saving time may have unintended health consequences. The American Academy of Sleep Medicine has already recommended adopting permanent standard time, arguing that it better aligns with natural biological rhythms and supports long‑term health.
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