Each March, we lose an hour of sleep when clocks spring forward for daylight saving time. If you dread this change more than the time change in November, there’s a good reason why.
“The time change in spring is harder on your body than the fall transition,” says Dr. Andrew Vernon, a medical director at BlueCross BlueShield of Tennessee. “It removes one hour of sleep, causing immediate sleep deprivation. The circadian rhythm, your body’s 24-hour clock, doesn’t adjust instantly. This creates a mismatch between biological time and social schedules.”
Why your body struggles with lost sleep
Dr. Vernon: The shift to daylight saving time disrupts more than just your alarm clock. Reduced morning light and increased evening light may disrupt circadian hormone signaling. Less morning light may lower serotonin, affecting mood and alertness. More evening light may suppress melatonin, delay sleep and shorten sleep duration.
Even one hour of lost sleep may affect attention and reaction time. Some studies have found a short-term increase in motor vehicle accidents following the time change in spring. It has also been associated with an increase in workplace injuries.
Some research has also observed increased cardiovascular events, including heart attacks, in the days after the spring transition.
Why falling back feels easier
Dr. Vernon: The fall transition adds an hour of sleep. This typically aligns better with natural circadian tendencies. The body adapts more easily to extra sleep than to forced sleep loss. The health risks seen in spring are less evident after the fall change.
Circadian adjustment can take several days to a week. Adolescents, shift workers and individuals with mood disorders are often more affected.
How to ease the transition
Dr. Vernon: Here are three strategies to help your body adjust:
- Prepare in advance. Shift bedtime earlier by 15-20 minutes for several nights before the change.
- Get bright light exposure early in the morning after the time change. Consider using a light box with 10,000-lux intensity in the morning if natural light is limited.
- Reduce caffeine and alcohol several days before and after the transition. Keep time for sleep and waking consistent and prioritize sleep during the first week.
“The good news is that after the switch to daylight saving time, evenings have more daylight,” Dr. Vernon says. “This increases opportunities for outdoor activity. But the transition requires preparation to help minimize health impacts.”
More from Dr. Vernon on WellTuned
Get more information about specific health terms, topics and conditions to better manage your health on bcbst.com. BlueCross BlueShield of Tennessee members can access wellness-related discounts on fitness products, gym memberships, healthy eating and more through Blue365®. BCBST members can also find tools and resources to help improve health and well-being by logging into BlueAccess and going to the Managing Your Health tab.