Navigating Daylight Saving Time: Strategies to Support Your Circadian Rhythm

It’s that time of year when daylight saving time will come to an end. This clock change of one hour creates a cascade of physiological disruptions that extend far beyond simple sleep loss. Let’s discuss ways to support your circadian rhythm through this adjustment period to minimize negative health effects & efficiently restore your natural sleep rhythm.

The Biological Reality of Daylight Saving

Transitions to and from daylight savings impose a “society-enforced” jetlag on your body. While the one-hour clock change may seem modest, the internal biological clock or circadian rhythm that governs sleep, hormone balance, metabolic rate, and countless other functions does not adjust so quickly.​

Our circadian rhythm operates on approximately a 24-hour cycle and is tightly regulated by the hypothalamus of the brain and clock gene expression throughout your body. The suprachiasmatic nucleus of the hypothalamus acts as your internal “master clock”, which responds primarily to light exposure throughout the day. Light exposure early in the morning advances your internal clock and evening light delays it.

Even a one-hour transition can alter the transcriptional profiles of core clock genes, leading to physiological changes that affect anything from metabolism to cardiovascular function. The liver, pancreas, and adipose tissue must all recalibrate, and this process takes several days or even weeks for some individuals.

Cortisol and the Stress Response

Cortisol is one of the body's primary stress hormones, but it is also a key regulator of the wake cycle. Under normal conditions, cortisol rises sharply upon waking and helps you feel alert and energized for your day. However, studies show that cortisol rhythms are significantly affected by daylight saving time transitions.​

We’ve learned in the last decade or so that for each hour delay in sunrise, median cortisol levels can increase by approximately 5%. (1) During the fall transition when clocks "fall back," many people experience elevated cortisol production as their biological clock struggles to align with the new schedule. This cortisol dysregulation contributes to the increased stress, irritability, and impaired cognitive function commonly reported after time changes.​

The spring transition creates different challenges. When you wake earlier relative to your biological clock, cortisol may not have peaked yet leaving you feeling sluggish and experiencing a groggy, disoriented state upon waking. Cortisol levels peak about an hour later during daylight saving time compared to standard time, which can make it changeling to feel ready for your day.

Melatonin and Serotonin Disruption

Light exposure also impacts both melatonin and serotonin.

Serotonin helps regulate mood, cognition, and general sense of happiness. Sunlight is necessary for proper serotonin production and activation. Low levels of morning light can contribute to decreased serotonin levels leading to low mood and the increase in depressive symptoms observed in hospitals following the fall time change.​ Serotonin is also a key precursor needed for melatonin production. (2)

Melatonin, which signals your body that it’s time for sleep, typically begins rising in the evening as daylight tapers. During changes in daylight saving time, extended evening light can suppress or delay melatonin secretion which makes it harder to fall asleep at your intended bedtime.

Metabolic and Cardiovascular Consequences

The metabolic implications of circadian disruption during time changes are substantial. Insulin sensitivity and glucose metabolism follow circadian patterns, with the body most efficient at processing glucose in the morning. Sleep deprivation and circadian issus lead to higher postprandial glucose levels and reduced insulin sensitivity.​ (3)

Evidence-Based Strategies for Circadian Adjustment

1. Gradual Sleep Schedule Shifts

The most effective approach to minimize circadian disruption is to begin adjusting your sleep schedule gradually the week before the time change occurs. Start by shifting your bedtime by 10-15 minutes each day for 5-6 days prior to the transition.​

For the spring "spring forward" transition, move your bedtime 10-15 minutes earlier each night.

For the fall "fall back" transition, shift bedtime 10-15 minutes later each night.

This incremental approach allows your circadian system to adapt progressively rather than experiencing an abrupt one-hour shift. This helps reduce the severity of symptoms like daytime sleepiness, irritability, and cognitive impairment.​

2. Strategic Light Exposure

Light is the most powerful tool for resetting your circadian rhythm, but timing of exposure is important.

For the spring transition, seek bright light exposure within 30-minutes of waking in the morning. This will advance your circadian phase earlier, helping you feel sleepy at an earlier time during the evening. Aiming for 10-15 minutes of natural light either outdoors or near a bright window would be ideal but, if this is unavailable, light therapy boxes providing 10,000 lux for 15-30 minutes can be effective.​ Also, be sure to minimize light exposure in the evening hours, particularly in the 2-3 hours before your target bedtime. Blue light from electronic devices is especially disruptive to melatonin production, so implementing a digital sunset by avoiding screens or using blue-light blocking glasses can help with falling asleep at a reasonable time.​

For the fall transition, it is still important to achieve light exposure within the first 30-minutes of waking but the bigger goal is to delay your circadian phase to stay awake later in the evening. Aim for additional bright light exposure in the afternoon and early evening as this will help delay melatonin production and keep you alert longer into the evening.

3. Consistent Wake Time as Your Anchor

Your circadian rhythm is guided primarily by your wake time versus sleep time, as the morning light exposure you receive upon waking is what resets your master clock.​

Set your alarm for the same time each morning. This consistency reinforces your healthy rhythm and prevents jetlag. While it may seem logical to sleep in after poor sleep to "catch up," this unfortunately works against your body's regulatory mechanisms and can perpetuate sleep difficulties. Therefore, it goes without saying that snoozing is a circadian rhythm no-no.

 

4. Exercise Timing to Support Circadian Adjustment

Even moderate physical activity provides benefits. Regular daytime exercise improves sleep quality, reduces stress, and strengthens circadian signaling.

5. Nap Times

Napping can either support or undermine your adjustment depending on timing and duration.​

If you experience severe sleepiness during the transition, a brief 15-20 minute "power nap" mid-day can improve alertness without significantly disrupting nighttime sleep. Longer naps or naps taken after 3pm can reduce sleep pressure and make it harder to fall asleep at your target bedtime.

6.     Minimize Caffeine and Alcohol

Both caffeine and alcohol disrupt sleep architecture and compound the challenges of time change adjustment.​

Caffeine blocks adenosine receptors, interfering with the “sleep drive” that builds throughout the day. As some individuals are slow caffeine metabolizers, it is important to establish a caffeine cutoff time of at least 6-8 hours before your target bedtime. For most people this caffeine cut-off time falls around 12-2pm.

Although alcohol can help put one to sleep given its sedating properties, it significantly impairs sleep quality by disrupting REM sleep, increasing sleep fragmentation, and causing more frequent awakenings. During these daylight saving transition periods, consider avoiding alcohol in the evening, particularly in the 3-4 hours before bedtime.

7. Optimize Your Sleep Environment

Proper sleep hygiene and cultivation of a healthy sleep environment become especially important in anticipation of circadian rhythm disturbances.​

• Maintain a bedroom temperature between 60-67°F (15-19°C), as your core body temperature naturally drops during sleep, and a cool environment facilitates this process.

• Make sure your bedroom is as dark as possible at night using blackout curtains or an eye mask.

• Minimize noise disruptions using white noise machines, earplugs, or sound-dampening materials.

• Avoid screens the 60-90 minutes before sleep as this can suppress innate melatonin production.

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Resources:

1.     Hadlow NC, Brown S, Wardrop R, Henley D. The effects of season, daylight saving and time of sunrise on serum cortisol in a large population. Chronobiol Int. 2014;31(2):243-251. doi:10.3109/07420528.2013.844162

2.     https://www.sciencedirect.com/science/article/pii/S0160412023006864

3.     Mason IC, Qian J, Adler GK, Scheer FAJL. Impact of circadian disruption on glucose metabolism: implications for type 2 diabetes. Diabetologia. 2020;63(3):462-472. doi:10.1007/s00125-019-05059-6