Increased Risk of Stroke After Daylight Savings Time

Recent studies have demonstrated that an effect on an individual’s internal clock can increase the risk of ischemic stroke. The objective of a new study was to determine if daylight savings time had an influence on this risk. In order to look at this connection, researchers analyzed decades of stroke data in Finland to identify the rate of stroke occurrence. The rate of stroke occurrence was identified in 3,033 hospitalized patients during the week after a daylight savings time change and this was compared to the rate of stroke in 11,801 hospitalized patients that was two weeks before or two weeks after that week.

Based off this comparison the researchers found that the overall rate of ischemic stroke was 8 percent higher during the first two days after a daylight savings time transition and no difference was observed after the two days. In addition, the researchers were also able to find that patients with cancer were 25 percent more likely to experience a stroke after a daylight savings time than during another period of time.

According to the National Stroke Association, a stroke is a brain attack that has the potential to happen to any individual at any time. A stroke is believed to occur when the necessary blood flow to a part of the brain is cut off, so cells do not receive the oxygen and begin to die. As a result of the blood cells dying during a stroke, a person’s ability to control parts of the brain that are responsible for memory and muscle control are lost. It is reported that a stroke occurs every 40 seconds and approximately 800,000 people experience a new or recurrent stroke each year. An ischemic stroke is one of the most common types of stroke in which the blood vessels that are responsible for carrying blood to the brain are blocked by a blood clot.

Recently researchers have proposed that turning the clock forward or backwards to coincide with daylight savings may be connected to an increased risk of a temporary ischemic stroke. Daylight savings is recognized as the practice of moving the clock one hours ahead during the summer months and this leads to evening daylight being experienced longer and back again in the fall to make better use of natural daylight. It has been found that many countries make better use of the natural light in the evenings and some studies show that daylight savings can lead to fewer road accidents and injuries by providing more daylight. The theory came from early study data presented at the 68th Annual American Academy of Neurology meeting in Vancouver, Canada.

These research findings serve as preliminary data towards achieving a better understanding of the association between daylight savings transition and increased risk of stroke and with this understanding comes the ability to help reduce the associated risk in patients.



EurekAlert (2016). Does daylight saving time increase risk of stroke?. Retrieved from

National Stroke Association (2016). What is stroke? Retrieved from

Time and Date (2016). Daylight savings time. Retrieved from


Author: Abimbola Farinde

Dr. Farinde is a healthcare professional who has gained experience in the field and practice of psychopharmacology/mental health, and geriatric pharmacy. She has worked with active duty soldiers with dual diagnoses of a traumatic brain injury and a psychiatric disorder providing medication therapy management and disease state management.


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