Daylight Savings: Health Effects and Tips

Medically Reviewed by Jabeen Begum, MD on February 29, 2024
7 min read

Daylight saving time (DST) is the period between March and November when people in most U.S. states move their clocks forward by an hour. In March, we "spring forward" to DST by setting our clocks ahead. In November, we "fall back" to standard time and set our clocks back.

Similar to jet lag, a time change like this can interfere with your body's sleep-and-wake cycles. It can cause sleep loss in the short term, and some health experts believe it may also have longer-lasting health effects.

Why do we have daylight saving time?

The idea behind DST is to gain more sunlight in the evening during spring, summer, and fall. It was first used in the U.S. during World War I as a temporary effort to save fuel, and it went into effect again during World War II.

In 1966, Congress passed the Uniform Time Act, making DST the national standard. But states can opt out of it. Arizona and Hawaii, both of which have plentiful daylight, don't participate. 

Changing your daily schedule can disrupt your circadian rhythm. That's your body's natural 24-hour cycle, which is strongly influenced by light. Light keeps your body from releasing melatonin, a hormone that promotes sleep.

This disruption can cause you to lose sleep, which not only makes you feel fatigued and grumpy but also affects your mental sharpness and productivity. Losing just an hour of sleep can throw off your internal clock for several days or more. 

You may be more prone to these effects if you work a night shift or otherwise tend to wake up later in the day, or if you're a teenager. The time change can also be upsetting to people with Alzheimer's disease and other types of dementia.

Many doctors believe long-term problems can result when our internal body rhythms are out of sync with the sun and seasonal changes. That's why the American Academy of Sleep Medicine and  American Medical Association have recommended that the U.S. remain on standard time year-round. 




Some research has shown that time changes resulting from DST may raise your risk for:

Heart attack. One study found a 24% higher risk for heart attack on the Monday after daylight saving time begins.

Stroke. Other research found that the risk of an ischemic stroke went up by 8% during the 2 days after both the spring and fall time changes.

Atrial fibrillation. Hospitalizations for this type of irregular heartbeat rise in the first 4 days after the spring time change, according to another study.

Mood changes. In one study, hospitals reported an 11% increase in depression symptoms shortly after the fall time change. More hours of darkness may play a role, since sunlight is linked to mood.

Accidents. Research found the risk for fatal vehicle accidents increased by 6% in the first week after the switch to daylight saving time.

You're also more likely to miss a doctor's appointment or to visit the emergency room shortly after the spring time change. 

Most of these effects are thought to be due to fatigue and lack of judgment due to sleep loss, as well as reduced immunity and body-wide stress that can result when your circadian rhythm is out of whack. 

Experts agree that it's harder to "spring forward" into daylight saving time than to "fall back" to standard time. One reason is that many of us lose an hour of sleep on the night of the transition.

Another is that, with the change to DST, those on typical work or school schedules are exposed to less light in the morning and more at night. This may lead to later bedtimes, which can result in long-lasting sleep deficits.   

When do we turn the clocks ahead?

In the U.S., daylight saving time officially starts at 2 a.m. on the second Sunday in March.

Spring forward sleep tips

Use these tips to help you spring forward easily and sleep better all year long:

  • Transition gradually. Start going to bed 15 minutes early several days before the change. Make an extra effort to be well-rested the week before the time change.
  • Seek sunshine.  The morning after DST begins, step outside and catch some rays soon after you wake up. Sunlight helps to reset your body’s internal clock.
  • Take a sleep break. If you feel sleepy after the change to DST, take a short nap in the afternoon -- but not too close to bedtime. Avoid sleeping in longer in the mornings. Your internal clock should adjust in several days.
  • Pace yourself. Try not to jam-pack your schedule right after the time change. Tackle important to-dos, like work presentations, later in the week if you can.  
  •  Drive safely. Be extra careful behind the wheel. Save that long-distance road trip for when you’re fully alert to lower your chances of getting into a car accident.
  • Know how much sleep you need. Not everyone needs the same amount of sleep to be well-rested, and sleep requirements can change with age. To find your ideal number of hours, sleep without an alarm on weekends and see when you wake up naturally.
  •  Keep regular sleep hours. Try to go to bed and wake up at the same time each day, including weekends, to help your body regulate its sleep pattern. Be aware of how  napping affects your sleep quality. For some, a nap makes nighttime sleeping harder; but for others, a short nap (20 minutes) can be revitalizing without ruining their night's sleep.
  • Get some exercise. Even moderate exercise, such as walking, can help you sleep better. Aim for at least 30 minutes of moderate movement, three times a week or more. If you often sleep poorly, don't exercise too close to bedtime.
  • Avoid stimulating substances. Alcohol and caffeine can interfere with sleep. If you have trouble sleeping, avoid alcohol and caffeine for 4 to 6 hours before bedtime. Smokers should avoid tobacco, another stimulant, too close to bedtime.
  • Eat lightly at night. Indigestion from spicy or fatty food, or just having too much food in your stomach, can cause insomnia. For a better night's sleep, eat light, simple foods several hours before bed. If you get hungry, have an easy-to-digest snack such as carbohydrates or dairy. Avoid drinking too much liquid before bed so that you don't wake up to go to the toilet.
  • Relax before bed. Stress and overstimulation make it hard to fall asleep. Avoid intense TV programs or movies before bed. Relax with a warm bath and curl up with a book instead.  If anxiety keeps you awake, write out your schedule for the next day before going to bed, including possible solutions to any challenges you're facing. If you're worried about hitting a deadline, get up early to work instead of working late into the night. 
  • Create a sleep-friendly environment. Try sleep shades, earplugs, a white-noise machine, blackout curtains, or all four. Temperature helps, too: 60-65 degrees is best. Also, you need a comfortable mattress. If you have restless or snoring pets, keep them out of your room, along with all electronics, including your phone and TV. Save your bedroom for sleep, sex, and relaxing.
  • Don't lie awake. If you can't fall asleep, or if you wake up and can't get back to sleep, don't watch the clock. This only creates more anxiety. If you're awake for more than 20 minutes, get up, go to another room and do something relaxing. Keep the lights low, have some warm milk, read a book, or write about whatever is on your mind until your eyelids get heavy.
  •  Avoid sleep aids. Taking melatonin at night could make you sleepy during the day. Some prescription sleeping pills can also make you less alert. Some can be addictive, too. Talk to your doctor before you try any sleep aid to learn about possible side effects and make sure it doesn’t interact with other meds you take.

You might think you gain an hour of sleep when daylight saving time ends in the fall. But research shows that most people actually lose sleep that night and over the next several days. An earlier bedtime may make it harder to fall and stay asleep. Moving the clock in either direction changes the main cue for our circadian rhythms -- light. 

People who routinely sleep less than 7 1/2 hours a night, and those who are early risers, tend to have a harder time adjusting.

When do we turn the clocks back?

The U.S. returns to standard time at 2 a.m. on the first Sunday in November. 

Fall back time change tips

How long it takes to adjust to the time change varies from person to person. But you may be able to speed up the process and feel more rested by following these tips:

Shift your bedtime later. Gradually adjust your sleep and wake times in the days before the change. On the night before DST ends, stay up for an extra hour past your usual bedtime. You might go ahead andchange your clock to give yourself a visual cue. 

Use light. Expose yourself to light during your waking hours as much as possible. And avoid bright light when it's dark outside. For example, use a nightlight instead of turning on an overhead light if you get up during the night to go to the bathroom.

Get moving. If your energy flags during the day, get some exercise -- outdoors, if possible. Twenty minutes of so of brisk walking should do the trick. Exercise helps you feel alert while you're doing it, and it promotes better sleep later on.

Practice good sleep hygiene. This is just as important during the fall time change as it is in the spring. The same rules apply: Avoid caffeine and alcohol, adopt a calming bedtime ritual, create a dark and quiet environment for sleeping, and stick to a regular sleep schedule. 

Be extra careful behind the wheel. It may be dark during your drive home from work, and fatigue can make driving riskier. Take extra care when driving in the dark, especially if you're tired.