Before heading to bed on Saturday, November 2, many Americans will set their clocks back one hour to prepare for the end of daylight saving time (DST). In the states that change clocks (Arizona and Hawaii are the only ones that do not), this “fall back” time is always the first Sunday in November.[1] This year, DST officially ends at 2 a.m. on Sunday, November 3, 2024, after an eight month run that began March 10. If you find yourself rejoicing each year over the extra hour of sleep, we hear you. But some medical experts say the extra slumber may have some unintended consequences for our health.
Here’s what you should know about the science behind why this time change may not be so great for health, and some tips for easing the transition.
Changing the Clocks on the Walls Can Throw Off Our Body Clocks Setting the clock back affects your body’s circadian rhythms — “the physical, mental, and behavioral changes in your body that follow a 24-hour cycle,” according to the National Institute of General Medical Sciences (NIGMS) definition.[2] Our bodies expect certain things to happen at certain times during the day (like sleeping, waking up, and eating) based on cues from the sun and on your doing those things over and over again at the same time every day. For example, says Aneesa Das, MD, a sleep medicine, internal medicine, and pulmonary disease specialist at The Ohio State University Wexner Medical Center in Columbus. “Natural sunlight during the day and the absence of light in the evening help to drive our circadian sleep phase.”
When you shift that routine — even by an hour — your circadian rhythms get slightly thrown off, similar to the effect of jet lag. The result: Your circadian rhythms become slightly misaligned from the time on the clock, which can throw off the timing of several daily processes that happen in the body, like sleep, digestion, and cardiovascular functioning.[3] And while many people may not feel all that affected by the change, large-scale data suggests that the risk of health problems like heart attacks and accidents may increase because of the change to and from DST.
One study that followed healthcare workers for eight years revealed an 18 percent uptick in safety-related human errors in the week following DST in the spring and a 5 percent increase after the end of DST in the fall.[4] Any disruption in the sleep or circadian cycle has the potential to increase risk of disease, says Matthew Morgan, MD, a primary care physician at Ochsner Health Center in Chalmette, Louisiana. Changes in daylight patterns — like the shorter days during fall and winter months — also affect your body’s normal sleep-wake cycle.
But those changes happen gradually over the fall months as the days get shorter (particularly in places farther north). DST clock changes happen overnight. “It can take several weeks for your circadian rhythm to adjust to the change that the end of DST brings,” adds Whitney Hardy, MD, a family medicine physician at Ochsner Health Center in Gretna, Louisiana.
Thanks, that was interesting!
But I wonder, if you accidentally put it in the wrong community. Or other way round: how is this related to open source?
(Or does my client show me some wrong information?)Sleep is FOSS now
Lost little Lemming…
Try these tips to help your body adjust quickly to the new schedule.
View Morning Sunlight
Circadian rhythms are the 24-hour cycles that regulate sleep, wakefulness, eating, and other activities. To adjust your circadian rhythms to the end of daylight saving time,** get plenty of natural morning sunlight in your eyes.** This light acts as an anchor for your internal clock,** **helping ensure the body’s cells and organs function optimally and at the right times.
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Get outside within 30-60 minutes of waking up to expose your eyes to sunlight.
- If you wake before sunrise, turn on bright artificial lights until the sun rises. Once it rises, get outside if possible.
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Try to get morning sunlight before the “circadian dead zone,” which occurs between 11 a.m. and 3 p.m. for most people but depends on your typical wake-up time.
- While sunlight exposure during this period has many benefits (e.g., mood, vitamin D and hormone levels), it won’t effectively shift your internal clock.
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This typically requires** about 10-15 minutes** of sunlight on a sunny day, while cloudy days may require 20 minutes or more.
- Even on overcast days, natural sunlight is usually brighter than artificial lighting.
- If natural sunlight isn’t an option for any reason, consider using very bright artificial lights or a light therapy lamp (ideally 10,000 lux or brighter).
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Avoid wearing sunglasses for your morning sunlight viewing, but glasses and contact lenses are fine.
- Always avoid staring directly at the sun or any intensely bright light sources at any time of day, as this can be painful and damage your eyes.
View Afternoon Sunlight
Make an effort to get outside again in the late afternoon when the sun is low in the sky or when it’s setting. Exposure to the late-afternoon sun helps adjust your eyes’ sensitivity and can buffer against the disruptive effects of artificial lights from screens and TVs in the evening.
- While morning sunlight is critical for setting your circadian clock, afternoon sunlight serves as a secondary cue, signaling the body to prepare for night.
Limit Nighttime Light
Dim or turn off artificial lights in your environment after the sun goes down. Remember, the sunset will now happen an hour earlier, given the time change.
- In the morning, we require a lot of bright light to set our circadian clock. Unfortunately, exposure to low levels of light (just 1,000–1,500 lux!) can disrupt circadian rhythms at night, especially short-wavelength light, such as blue light.
- After sunset and in the hours before bedtime, opt for dim, low-positioned lights, such as table lamps, instead of overhead lights. This low ambient light supports natural melatonin production and makes it easier to fall asleep.
- To help avoid short-wavelength light (blue and green light) after sunset, consider shifting screen settings to a red tint, using red “party” lights instead of LED or fluorescent lights, or wearing red-lens glasses.
To maintain healthy sleep patterns, keep your bedroom dark and minimize light exposure during sleep hours.
Strive for Consistent Sleep/Wake Times
Aim to go to sleep and wake up at roughly the same time each day, ideally within a 45-minute to one-hour window, even on weekends. This consistency reinforces your circadian rhythm and makes it easier to fall asleep and wake up feeling refreshed.
- Check out our Improve Your Sleep and Toolkit for Sleep newsletters for more on enhancing sleep.
Leverage Temperature, Meals & Exercise
While light is the primary method for adjusting our circadian clock, temperature, exercise, and meal timing also play important roles.
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If you’re struggling to adjust to daylight saving time, temperature can be a powerful tool to shift your circadian clock.
- Taking a warm bath or shower before bedtime is a science-supported method to improve your ability to fall asleep and sleep deeply. Initially, the warm water raises core body temperature, but the subsequent cooling that occurs afterward helps facilitate falling asleep.
- Keep your bedroom cool (about 67°F or 19.4°C), or consider using a temperature-controlled mattress cover.
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To adapt quickly to the end of daylight saving time, wait to eat until your usual mealtime at the new time, even if you feel hungry beforehand.
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Exercise significantly enhances sleep quality and duration. Sticking to your regular exercise schedule will also help your body adjust effectively.
The above text is from the Huberman Lab newsletter.
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Am I the only person whose natural clock has me waking up later and later up to this point b/c of sunrise, and when this time change kicks in I’m back to waking up at the appropriate time and feeling amazing?
Hard to believe this is bad for me in any way. In point of fact, I don’t understand why we just don’t keep the clocks here.
