TWR #12 Why Winter Is Ruining Your Sleep (According to Your Circadian System)
Nutriburst Vitamins
December 12, 2025
Closer look at the trend
SAD lamps. Sleepmaxxion hacks. Red-light rituals. Morning sunlight challenges. Winter has turned sleep into a cultural obsession.
But here’s what the trends don’t explain: Your sleep isn’t failing but your circadian system is reacting to winter. And no number of gadgets can override a biological environment that’s completely shifted.
What the Circadian System Actually Is
Your circadian rhythm is your body’s 24-hour internal timing system. It controls when you feel awake, tired, hungry, focused, warm, or calm – all by responding to environmental cues like:
- Light
- Temperature
- Movement
- Food timing
When those cues are strong and consistent, your body runs in sync. In winter, they aren’t. And here’s what happens next.
1. Light cues collapse
Morning light is the strongest signal for aligning the circadian rhythm. Research shows that reduced light exposure in winter delays the timing of melatonin secretion — the hormone that regulates sleep onset.
This delay shifts your entire sleep–wake cycle later, which explains the grogginess, afternoon crashes, and “awake at night” feeling common in winter.
2. Temperature Signals Get Confusing
Your body relies on a steady decline in core temperature to fall asleep and stay asleep. Studies have found that inconsistent temperature environments — like cold exposure outdoors followed by overheated indoor spaces — disrupt the natural cooling pattern needed for consolidated sleep.
This leads to lighter, more fragmented sleep throughout the night.
3. Inflammation Quietly Rises
Winter habits change: less movement, heavier foods, more indoor time. Evidence suggests that these seasonal shifts increase low-grade inflammation, which interferes with both deep sleep and REM sleep, reducing how restorative your sleep feels even if you’re technically sleeping enough hours.
4. The Nervous System Falls Out of Rhythm
Serotonin and cortisol respond directly to changes in daylight. Research shows that shorter days reduce serotonin activity and contribute to higher evening cortisol levels — a pattern strongly associated with difficulty winding down, delayed sleep onset, and the classic winter paradox: tired during the day, wired at night.
What Actually Helps (Biology, Not Hacks)
Better sleep in winter comes from strengthening the cues your circadian system relies on:
- Morning light exposure – even grey outdoor light re-anchors your body clock
- Hydration + electrolytes to stabilise thermoregulation
- Evening wind-down cues that calm the nervous system
- Foundational nutrients (B vitamins, magnesium, antioxidants, adaptogens) to support neurotransmitters and reduce inflammatory sleep disruption
These aren’t trends – they’re physiological levers.
Our Take
We don’t see sleep as something you “hack”. Especially in winter, it’s something you support at the system level.
Strong morning cues, a calm nervous system, steady hydration, and essential nutrients help the body regulate itself — far more powerfully than another gadget on your bedside table.