Winter in Canada often leads to fatigue due to shorter daylight hours, colder temperatures, and longer nights, which disrupt our natural sleep-wake cycle. Reduced sunlight lowers serotonin and increases melatonin, making us feel sleepy earlier and throwing off our circadian rhythm. These changes, combined with factors like Seasonal Affective Disorder (SAD), can leave us feeling sluggish and tired.
Circadian Rhythm and Winter Fatigue
What is Circadian Rhythm?
Your circadian rhythm is your body’s internal clock that regulates sleep, energy, and hormone production.
How does Circadian Rhythm affect energy in winter?
Your circadian system times hormones like cortisol (alertness) and melatonin (sleep). In winter, less sunlight delays cortisol production, causing fatigue and low energy.
What is SAD (Seasonal Affective Disorder)?
SAD is a seasonal depression linked to reduced sunlight. Symptoms include fatigue, low mood, and oversleeping. In Canada, 2–3% experience severe SAD; up to 15% have milder symptoms.
(Source: Canadian Mental Health Association)
Quick Facts: Sleep Health in Winter
- Canadians sleep 30–45 minutes longer in winter but report lower sleep quality.
- Vitamin D deficiency is common due to limited sunlight.
- Blue light exposure from screens worsens circadian disruption.
Sleep Reset Tips for Winter
- Spend 20–30 minutes outdoors in morning light.
- Maintain a consistent sleep schedule by going to bed and waking up at the same time daily.
- Limit screen time before bed.
- Exercise to boost serotonin and energy levels.
- Include Vitamin D-rich foods like salmon and fortified dairy.
When Winter Fatigue Becomes Insomnia
Feeling tired in winter is common but if you struggle to fall asleep, wake up often, or feel exhausted despite enough sleep, you may have insomnia. Unlike seasonal fatigue, insomnia persists for weeks or months and affects daily functioning.
CBT-I (Cognitive Behavioral Therapy for Insomnia) is the treatment recommended by sleep specialists worldwide. It’s drug-free, evidence-based, and focuses on resetting your sleep patterns for lasting results.
Book a CBT-I session today with our certified sleep therapists and start sleeping better naturally.
Frequently Asked Questions
Shorter daylight reduces serotonin activity and extends melatonin’s duration, shifting circadian timing so evenings feel sleepier and mornings groggier. Colder weather and less outdoor time add to fatigue.
Light cues align your internal clock. With less morning light, the cortisol awakening response can be delayed while melatonin lasts longer, blunting morning alertness.
A recurrent, seasonal depression pattern tied to reduced light. In Canada, ~2–3% experience SAD and up to 15% have milder winter blues. [bc.cmha.ca]
Morning outdoor light (20–30 min), consistent sleep/wake times, screen‑light reduction before bed, regular exercise, and Vitamin‑D‑rich foods or appropriate supplementation guidance.
Yes—large datasets show sleep duration is typically ~15–20 minutes longer in winter in the Northern Hemisphere. [academic.oup.com]
If difficulty sleeping persists for weeks with daytime impairment, it’s likely insomnia rather than seasonal fatigue—CBT‑I is the first‑line treatment.