Daylight Saving Time Health Effects: Sleep, Gut Health, and Circadian Rhythm

Sunday, March 8, 2026, may mark the last time British Columbia “springs forward.” The provincial government has moved forward with the plan to stay on Daylight Saving Time (DST) permanently, ending the twice-yearly practice of changing clocks. Officials say this will make life easier for families, reduce disruption, and provide more usable light in winter evenings.

Yet many health experts warn that this choice may have significant implications for our health.¹˒²

Let’s unpack why this matters.

How does Daylight Saving Time affect health? TL;DR

Daylight Saving Time can affect health by disrupting the body’s circadian rhythm—the internal clock that regulates sleep, digestion, hormones, and metabolism. When social clock time shifts away from natural sunlight patterns, especially in northern regions like British Columbia, this misalignment may contribute to poorer sleep, digestive symptoms, fatigue, and changes in mood.

Circadian Rhythms: More Than Just Sleep

You may have heard the term circadian rhythm before, but let’s explore what it actually means and how it influences your day-to-day functioning.

Circadian rhythms are internal biological rhythms that regulate many processes on a roughly 24-hour cycle. The term comes from the Latin circa (around) and diem (day), meaning “around a day.”

While we have other biological rhythms that occur on shorter and longer timelines, some of the most notable processes governed by circadian rhythms include:

• sleep

• digestion

• hormone release

• immune function

These rhythms are most naturally synced to the sun’s light–dark cycle, not the clock on the wall.

Our internal body clock keeps time based on light signals—most powerfully from the sun. In today’s modern environment, it also receives light input from electronic devices and artificial lighting.

The body clock is designed to respond to light exposure:

• Bright light activates the system, promoting alertness and activity.

• Dim light or darkness signals the body to wind down.

In other words, we are biologically designed to be awake, active, and eating during daylight hours, and resting and sleeping at night.

When our lifestyle no longer aligns with natural light patterns, we can experience something called chronodisruption—a mismatch between internal and external cues that disrupts normal physiological processes.

This phenomenon is commonly seen in shift workers and people who frequently cross time zones (such as airline crew or frequent travellers). Research has consistently shown that misalignment between internal circadian time and external clock time is associated with metabolic disturbances, including impaired glucose regulation, appetite dysregulation, and increased cardiometabolic risk.⁴

Permanent DST effectively shifts clock time to be later than the sun’s natural schedule.

During the spring and summer months, this may be less noticeable because the sun rises very early—as early as ~4:00 AM in some regions. However, during winter months, sunrise may occur much later in the morning—sometimes as late as 10:00 AM in parts of British Columbia.

This means many people would begin their day in darkness rather than natural morning light.

This isn’t a small detail—morning light is one of the strongest signals for resetting our circadian rhythm each day.⁴˒⁵

Daylight Saving Time Health Effects: Digestion, Energy, and Mental Health

When our internal circadian rhythm becomes misaligned with the external clock—a phenomenon known as circadian misalignment—the effects extend far beyond simply feeling tired.

Because many physiological systems follow daily rhythms, even small shifts in timing can influence digestion, metabolism, and mental health.

The Canadian Sleep Society warns that adopting permanent DST could prolong circadian misalignment, particularly in northern regions where winter sunrise already occurs later in the morning. While the society supports eliminating seasonal clock changes, its position statement recommends permanent Standard Time—not DST—as being most aligned with human circadian biology.³

How Circadian Disruption Affects Digestion

One of the systems affected by circadian disruption is the digestive system.

The digestive system has its own circadian rhythms that influence:

• gastric emptying

• digestive enzyme production

• intestinal motility

• the activity of the gut microbiome

Research suggests that when eating and sleeping patterns occur at biologically “unexpected” times, digestive processes may become less efficient. This can lead to symptoms such as:

• bloating

• reflux

• irregular bowel habits

• abdominal discomfort⁶

Shift-work research provides some of the clearest evidence of this effect. Individuals who regularly experience circadian disruption—such as nurses working overnight shifts—report significantly higher rates of gastrointestinal complaints including indigestion, constipation, and irritable bowel symptoms.⁶

This likely occurs because digestion is naturally programmed to function optimally during the daytime, while nighttime is biologically designated for rest and repair.

Circadian misalignment may also affect how the body processes nutrients and regulates appetite. Disrupted sleep-wake cycles can impair glucose regulation, alter hunger hormones such as leptin and ghrelin, and increase cravings for highly palatable foods. Over time, this pattern may contribute to increased cardiometabolic risk.⁴˒⁵

Circadian Rhythms and Mental Health

Energy levels and mental health are also closely tied to circadian timing.

When morning light exposure is delayed—as may occur during darker winter mornings under permanent DST—our body clock may shift later. This can make it harder to fall asleep at night and more difficult to wake in the morning, creating a cycle of chronic sleep restriction.

Common consequences include:

• persistent fatigue

• reduced concentration

• lower productivity

Light exposure also plays a key role in regulating neurotransmitters involved in mood. Reduced morning light and delayed circadian timing have been associated with increased risk of depressive symptoms and seasonal mood changes—particularly for people living in British Columbia and other northern regions, where winter daylight hours are already limited.⁷˒⁸

In other words, when the clock shifts away from the sun’s schedule, the ripple effects can affect multiple aspects of health—from how well we digest our meals to how energized and emotionally balanced we feel throughout the day.

Body System	Possible Effects of Circadian Disruption
Sleep	Difficulty falling asleep, reduced sleep quality, daytime fatigue
Digestion	Bloating, reflux, irregular bowel movements
Metabolism	Changes in appetite hormones and glucose regulation
Mental health	Mood changes, seasonal depression, reduced concentration

Circadian rhythms influence multiple biological systems, which is why even small shifts in sleep timing or light exposure can affect overall health.

What You Can Do to Support Your Body Clock

While individuals cannot control time policies, there are practical steps you can take to help support your circadian rhythm.

1. Be intentional about light exposure

Aim to get outside into natural light within the first hour of waking, even on cloudy days. A short walk, morning coffee outdoors, or commuting on foot (even partially) can all help.

During darker winter months, some people benefit from a clinically approved light therapy lamp used shortly after waking, such as this Canadian-made option or this option.

In the evening, try to reduce light exposure—especially from phones, tablets, and computers. Dimming lights and limiting screens 1 hour before bed can help signal to your brain that it’s time to wind down.

2. Support your gut

Dietary patterns that support the gut microbiome may help buffer some of the effects of circadian disruption.

Focus on foods rich in dietary fibre and a diversity of plant foods, such as:

• whole grains

• legumes

• vegetables

• fruits

• nuts and seeds

Fermented foods like yogurt and sauerkraut may also support microbial balance and digestive function. And don’t forget to hydrate!

Unsure how to incorporate these foods into your routine? Get in touch.

3. Align meals with daytime hours

Because digestion follows circadian rhythms, eating during our more active daytime hours—and minimizing late-night meals—may support better metabolic and digestive function.

Aim for consistent meal timing and try to finish your last substantial meal 2–3 hours before bedtime.

4. Keep consistent sleep and wake times

Your body clock thrives on routine. Maintaining a relatively stable sleep and wake schedule—even on weekends—helps anchor circadian rhythms and can improve both sleep quality and daytime energy.

5. Move your body

Regular physical activity can strengthen circadian rhythms, improve sleep quality, and support mental health.

When possible, combine movement with bright light exposure—such as a morning workout or lunchtime walk—but any movement that fits into your schedule is beneficial.

Bonus: Stay informed and advocate for health-supportive policies

If the issue of permanent DST matters to you, consider sharing your perspective with local representatives or participating in public consultations.

Some sleep scientists advocate for permanent Standard Time, which may better align with human circadian biology.

Frequently Asked Questions

Does Daylight Saving Time affect digestion?

Possibly. The digestive system follows circadian rhythms that regulate gastric emptying, enzyme production, and gut motility. When sleep and meal timing shift away from natural daylight hours, digestive processes may become less efficient, which can contribute to symptoms such as bloating, reflux, or irregular bowel habits.

Is permanent Daylight Saving Time healthy?

Many sleep and circadian rhythm experts caution against permanent Daylight Saving Time and the subsequent delayed morning light exposure in winter months, which can shift the body’s internal clock later. Several scientific organizations recommend permanent Standard Time instead because it more closely aligns with human circadian biology.

How can I support my circadian rhythm?

Supporting circadian health involves regular exposure to morning light, consistent sleep schedules, regular meal timing, and limiting bright light exposure late in the evening. Physical activity and fibre-rich dietary patterns may also support metabolic and digestive rhythms.

The Bottom Line

Our bodies evolved to follow the rhythm of the sun, and when social schedules shift away from natural daylight patterns, daylight saving time health effects can appear in subtle but meaningful ways. When our social schedules drift away from that rhythm, the effects can appear in subtle but meaningful ways—from digestive discomfort to persistent fatigue and mood changes.

While the broader time-policy debate continues, focusing on daily habits that support circadian alignment—light exposure, consistent sleep, thoughtful meal timing, and gut-supportive nutrition—can make a meaningful difference.

If you’re struggling with energy, digestive symptoms, or irregular eating patterns related to sleep disruption, working with a registered dietitian can help.

Learn more or book a nutrition consultation here.

References

1. Government of British Columbia. B.C. moves forward with plan to end seasonal time changes. Published 2026. Accessed March 2026. https://news.gov.bc.ca/releases/2026AG0013-000209

2. CityNews Vancouver. Experts slam B.C. moving to daylight time for good. Published March 3, 2026. Accessed March 2026. https://vancouver.citynews.ca/2026/03/03/experts-slam-bc-moving-to-daylight-time-for-good/

3. Canadian Sleep Society. Position statement of the Canadian Sleep Society on the practice of Daylight Saving Time (DST). Accessed March 2026. https://css-scs.ca/society-news/position-statement-of-the-canadian-sleep-society-on-the-practice-of-daylight-saving-time-dst/

4. Roenneberg T, et al. Chronodisruption and its effects on metabolism and health. Biology (Basel). 2019;8(3):54.

5. National Research Council Canada. Sun calculator. Accessed March 2026. https://nrc.canada.ca/en/research-development/products-services/software-applications/sun-calculator

6. Centers for Disease Control and Prevention. Long work hours and shift work: gastrointestinal effects. Accessed March 2026. https://www.cdc.gov/niosh/work-hour-training-for-nurses/longhours/mod3/17.html

7. Huang T, et al. Circadian rhythm disruption and mental health outcomes. Front Psychiatry. 2024.

8. Walker WH, et al. Light exposure, circadian timing, and mood disorders. Front Neurosci. 2024.