How daylight saving time can affect sleep

Twice a year, hundreds of millions of people in the U.S. reset their clocks for daylight saving time. While the change is meant to make better use of daylight, it also shifts when people’s bodies expect to sleep and wake up. For some, the adjustment is quick and painless. For others, that one-hour change can disrupt sleep, affect alertness and make the days following the switch harder than expected.

But why is that, and are there ways to help avoid the negative effects of daylight saving time? Here’s how the clock change may affect sleep, why it can have a bigger impact on health than many people realize and why some people have a harder time adjusting in the days and weeks that follow.

In this article:

What is daylight saving time?

Daylight saving time is the stretch of the year between spring and fall when most of the U.S. moves clocks forward by one hour. It starts on the second Sunday in March and ends on the first Sunday in November. These dates are set by law, but for most people, it just means we “spring forward” to enjoy a little more evening daylight and “fall back” later in the year to return to standard time.

How does daylight saving time affect sleep?

Circadian rhythms are the natural 24‑hour cycles that influence many of the body’s physical, mental and behavioral processes. They help regulate essential functions like sleep patterns, hormone levels, appetite, digestion and body temperature. When people switch between standard time and daylight saving time twice a year, the timing of their light exposure shifts.

Normally, bright daylight promotes alertness, while evening darkness triggers sleepiness. But when daylight saving time shifts the clock by an hour, it may change how much light someone gets at key times of day. People suddenly may get much less light in the morning, which can trick the brain into thinking it’s still nighttime and that the body should still be asleep. As a result, people may feel groggy or not fully alert. And then at the same time, increased light in the evening can push bedtime later, making it harder to fall asleep.

For adults specifically, anyone getting less than 7 hours of sleep a night consistently may be at an increased risk of heart attacks, asthma, depression and stroke.

How to help improve sleep during daylight saving time

When daylight saving time begins, people may feel more tired and notice their sleep schedule getting thrown off. The good news is that there are a few simple things people can do to help stay functional and feel well‑rested during the time change:

• Prioritizing sleep. Sleeping enough every night can help with someone's health. Make sure to prioritize sleep. Everybody is different, but in general, people should aim for the recommended amount of daily sleep for their age group.
• Shift schedule gradually. In the spring, people can consider going to bed 15 to 20 minutes earlier each night for a few days before the time changes. In the fall, doing the opposite by staying up 15 to 20 minutes later to help the body adjust.
• Using light to an advantage. In the spring, people should try to get outside for some sunlight on Sunday morning and keep lights dim in the evening. In the fall, limiting light exposure until someone’s usual wake-up time. This may help reset the body’s internal clock and makes the transition easier.

Why sleeping well is important

Sleep is essential for overall health and well‑being at every stage of life. How someone feels during the day has a lot to do with what happens while they sleep. During rest, the body recharges, and the brain forms long‑term memories. And for kids and teens, sleep helps with growth and development.

When people get good, consistent sleep, they tend to get sick less often, maintain a healthier weight, feel less stressed and improve their mood. But not getting enough sleep or waking up repeatedly throughout the night can potentially lead to problems, including:

• A higher risk of serious health issues, including coronary heart disease, high blood pressure, obesity and stroke.
• Decreased physical activity, which can lead to weight gain.
• Overeating, especially fatty, sweet or salty foods.
• Trouble concentrating, staying focused and thinking clearly.

How much sleep is recommended?

Here’s a quick look at how much sleep people typically need at different ages — including nap time.

Consult with a health care provider if someone consistently struggles with sleep or experiences excessive fatigue.

Key takeaways

It’s amazing how something as small as a one‑hour shift can throw our routines off balance. Daylight saving time can disrupt the body’s internal clock by shifting light exposure and sleep timing, making it harder for some people to fall asleep, wake up feeling rested and stay alert. While the effects are usually temporary, prioritizing sleep and making small, gradual adjustments can help the body adapt more smoothly and reduce the impact on overall health.

This content is for informational purposes only and is not medical advice. Consult your health care provider before taking any vitamins or supplements and prior to beginning or changing any health care practices.