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How Daylight Savings Affects Your Brain
Cognitive Research

How Daylight Savings Affects Your Brain

Published: 06/11/2023

Written by: Creyos

Twice a year, North Americans adjust our clocks for daylight savings time (DST). Over the years, there has been tons of public conversation about whether changing our clocks truly provides the social and economic benefits it claims. From optimizing daylight hours to reducing energy consumption. When our bodies and brains feel the effects, if only for a few days, it doesn’t seem worth it.

Whether we are at the point of the year where we “spring forward” or “fall back”, each of these events is still a sudden shift in our daily rhythms. Do the disruptions of daylight saving affect how well our brains work?

In 2023, daylight savings time will take place from Mar 12, 2023 – Sun, Nov 5, 2023, after which we return to standard time. On Sunday, November 5, 2023 at 2 am, daylight savings time ends.

Daylight savings time happens on roving dates:

  • Spring forward: Takes place at 2am on the second Sunday in March. This is the “bad” part, when we clocks ahead by an hour and we lose an hour of sleep.
  • Fall back: Takes place at 2am on the first Sunday in November. This is the “good” part, when we clocks back an hour and we gain an hour of sleep.

Read on to learn how daylight savings impacts our brain health, from sleep to mental health to cognition.

Effects of Daylight Savings on Sleep

We can’t talk about the impacts on the brain and body without talking about how daylight savings affects sleep. We’ve discussed before how a change in schedule can result in “social jet lag,” affecting sleep, which affects cognition. Daylight savings time provides a natural experiment, in which large parts of the country change their sleep schedules all at once.

What research finds is that a change in the circadian rhythm has effects that last for several days. Light is a powerful cue for regulating our circadian rhythm. It evokes wakefulness with morning light and sleepiness with evening darkness.

When the clocks change, our rhythms of waking and first exposure to morning light change, too. With this comes compromised sleep quality, sleep debt, and reduced cognitive function—especially during the first few hours of waking.

How Daylight Savings Affects Your Brain

In connection to its effects on sleep, daylight savings affects the brain by impairing cognitive function. With disruption to the circadian rhythm comes lingering effects on productivity and wakefulness, which can lead to increased injury too.

  • Workplace injuries increase on Mondays after daylight saving starts. There is no corresponding decrease when it ends
  • “Cyberloafing”—browsing the Internet to slack off at work—increases the Monday after DST

Many of the consequences of shifting our clocks are personal, but these effects ripple out into societal consequences. The decreased productivity seen on the Monday after DST can affect the stock market. One paper estimated a $31 billion one-day loss on the major stock exchanges in the U.S. on that fateful Monday.

Effects of Daylight Savings on Mental Health

Daylight savings time can also affect mental health, especially for people already living with mental illness who are vulnerable. Both shifts, into and out of daylight savings, have been associated with mood disturbances due to the connections between sleep and mental health.

The end of daylight savings also coincides with the time of year people are likely to start experiencing the effects of seasonal affective disorder (SAD). According to the American Psychiatric Association, about 5% of adults in the U.S. experience SAD, and it typically lasts about 40 percent of the year. Much like the effects of daylight savings, SAD is linked to biochemical changes that come from less exposure to sunlight during the winter months and changes to sleep patterns.

Many of the symptoms of SAD can be amplified by DST, like feelings of:

  • Guilt from a lack of productivity
  • Purposelessness or lack of motivation
  • Fatigue or lack of energy
  • Sadness or depressive mood

How Daylight Savings Affects Your Body

Mental health, sleep, and physical health are so closely interconnected. So when the clocks shift during daylight savings, our bodies feel the effects too.

When we get an extra hour of sleep:

  • Rates of heart attacks decreased in the day following the end of daylight savings

Conversely, when we lose an hour of sleep, research indicates:

  • Rates of heart attacks increase for three days following the start of daylight savings
  • Rates of arrhythmia and atrial fibrillation increase for four to seven days following DST
  • Rates of stroke increase for the first two days

These patterns in acute myocardial infarction are best explained by the adverse impacts of sleep deprivation on cardiovascular health.

Each of these conditions was measured, in part, by the increase in emergency room visits and return visits to the hospital that correspond with the shift to the spring transition from standard time to DST. Unfortunately, the negative effects of daylight savings on the body are also compounded by an increase in missed medical appointments, caused simply by people failing to set their clocks properly.

People are clearly more at risk during the first few days of daylight savings—physical health takes a toll through increased distress and sleep disturbance. But physical health can also be affected by injury, such as when traveling to a medical appointment.

Could telehealth be a solution for healthcare continuity after daylight savings that reduces risk of injury? Read more: Six Reasons Why Telemedicine is Here to Stay

Is Daylight Savings Bad For Our Health?

If daylight savings is terrible for the brain, health, and even our economy, why do we continue doing it every year? While the research shows the start of daylight savings effects us more dramatically than the ending, both are associated with adverse health effects—even if only temporarily. These impacts form a pretty compelling argument for why we shouldn't have daylight savings time any longer. But still, many advocate for it's benefits, such as reduced traffic collisions when there is more daylight during high-traffic times.

If you're feeling the cognitive and emotional effects following daylight savings, you're not alone. It can be helpful to know what's causing this shift and that it's likely to last only a few days.

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