The month of March heralds spring in the Northern Hemisphere and throughout the month many countries move their clocks one hour forward to gain an extra hour of daylight. What can we do to limit the effects of daylight savings time on our health?
Daylight saving time (DST) affects the human biological clock, concentration, eating, and sleep patterns. These disturbances can affect people in various ways. Research shows that while adjusting to DST, there is a temporary spike in the incidence of road accidents and strokes. On the plus side, however, that extra hour of daylight promotes serotonin secretion – one of the “happy hormones” that improves mood and encourages physical activity. Sun exposure boosts vitamin D production, essential for bone and immune health and metabolic balance. Exposure to natural light enhances wakefulness and sleep via the secretion of melatonin.
Sleep plays a crucial role in our health. For children, good sleep contributes to their developmental health; in adults, sleep contributes to mental and physical recovery. However, losing an hour of sleep on the first night of DST disrupts our biological clock and physiological functions. The combination of that disturbance, delayed sleep, and sleep difficulties can merge to create a cycle of increased fatigue. Furthermore, people with rigid sleep routines may have a hard time adjusting and those with preexisting health conditions, such as mood disorders or chronic illnesses, may experience worsening symptoms.
The Link Between Time Changes and Migraines
Dr. Erel Domany, a senior physician at the Department of Neurology and Head of the Headache Clinic at Rambam Health Care Campus (Rambam) in Haifa, Israel, explains that time changes—including DST—can trigger chronic headaches and migraines. “Migraine sufferers are particularly sensitive to shifts in sleep patterns and light-dark cycles, which trigger them,” he says. “Similarly, those with cluster headaches, which tend to flare up during seasonal transitions, may experience worsening symptoms.”
Studies also show a rise in strokes and seizures among epilepsy patients during the week following a time change, likely due to disruptions in biorhythms and sleep quality. Individuals with dementia or Alzheimer’s may also face heightened difficulties during this period.
DST and Fertility
In the animal kingdom, daylight is a biological cue for reproductive cycles—longer daylight hours lower melatonin levels, which promote reproduction. Conversely, in winter, higher melatonin levels may suppress reproductive hormones.
“In humans, seasonal birth trends exist, though they are less pronounced and vary by region,” explains Dr. Ola Gutzeit, a senior physician in the Division of Obstetrics and Gynecology and head of the Fertility Preservation Clinic, IVF Unit at Rambam. “In July and August, we observe a 5% increase in births at Rambam compared to the annual average, possibly reflecting biological processes from earlier in the year. Also, daily and nightly fluctuations in in melatonin affect our biological clock and hormone production."
While changing the clock does not affect the number of daylight hours, temporary sleep deprivation may occur. However, research suggests that short-term disruptions—such as DST—are unlikely to impact fertility significantly.
Dealing with DST
Transitioning through DST is more difficult than reverting to wintertime when an hour of extra sleep is gained. However, there are a few ways to improve sleep quality: go to bed a little earlier in the days preceding the time change; avoid bedtime and nighttime screen exposure; strenuous physical activity at least two hours before bedtime; calming activities before bedtime, like reading, listening to relaxing music, are helpful, and get some extra exposure to the sun and daylight during the first days of DST.
Although adjusting to DST can be challenging, it has several benefits. It is an opportunity to engage in fun and positive activities. And everyone can use a little extra light during this challenging time.