Circadian Rhythm and Winter Health Managing Body Clock for Fatigue, Cravings, and Sleep After the Clocks move back
- JDR nutrition
- 7 days ago
- 3 min read
At the end of October, the clocks go back, and while this is only a one-hour shift, it has measurable effects on the body. The reason lies in the circadian rhythm – our internal body clock – which regulates sleep, hormone release, metabolism, and even appetite. When the rhythm is disrupted, the knock-on effects include fatigue, cravings, poor sleep quality, and changes in mood.
The circadian rhythm explained
The circadian rhythm is a 24-hour cycle controlled by a part of the brain called the suprachiasmatic nucleus (SCN), located in the hypothalamus. The SCN receives information about light and darkness from the eyes and synchronises many processes in the body accordingly.
This rhythm controls:
When we feel alert and when we feel tired.
The release of key hormones.
How we metabolise food at different times of the day.
Core body temperature and immune function.
Key hormones and their roles affected by circadian rhythm
Cortisol: Should rise in the morning, peaking within the first 30–60 minutes after waking (the “cortisol awakening response”), helping us feel alert and energised. Cortisol should gradually fall across the day. When disrupted, people may feel groggy on waking and “wired” at night.
Melatonin: Released in response to darkness in the evening, preparing the body for sleep. Exposure to artificial blue light in the evening suppresses melatonin release and delays sleep.
Insulin: Sensitivity to insulin is higher earlier in the day, meaning the body processes carbohydrates more efficiently in the morning than in the evening. This explains why late-night eating is linked with higher blood sugar and weight gain.
Leptin and ghrelin: These regulate hunger and satiety. Poor sleep and circadian disruption lower leptin (the fullness hormone) and raise ghrelin (the hunger hormone), driving appetite and cravings – particularly for sugary, high-calorie foods.
What happens to our circadian rhythm when the clocks go back?
When the clocks change, the shift in light exposure disrupts the circadian rhythm. Even a single hour can cause:
Difficulty falling asleep or waking at the “new” time.
Increased cravings for carbohydrate-rich “comfort foods”.
Afternoon energy dips.
Lower mood due to shorter daylight hours.
If circadian disruption continues, it can contribute to long-term health issues including insulin resistance, weight gain, raised blood pressure, low mood, and poor immune function.
Light: the primary regulator
Light is the most powerful cue for the circadian rhythm. Different wavelengths affect the body differently:
Blue light in the morning: Found in natural daylight, this stimulates cortisol, supporting alertness and resetting the circadian clock.
Blue light in the evening (from screens and LED bulbs): Suppresses melatonin and delays sleep onset.
Red/orange light in the evening: These wavelengths do not interfere with melatonin release, which is why firelight, candlelight, or red-shifted lamps support winding down before bed.
Practical strategies to support your circadian rhythm
Morning and daytime:
Get outside within an hour of waking, even on cloudy days. 15–20 minutes of outdoor light is enough to reset the clock.
If mornings are very dark, consider a dawn-simulation lamp or a medical-grade SAD light box.
Position your workspace near a window where possible.
Evening:
Dim overhead lights after sunset.
Use warmer bulbs or lamps with red/orange tones.
Reduce screen time in the 2–3 hours before bed. If this isn’t possible, use blue light filter apps (Night Shift, f.lux) or blue-blocking glasses.
Consider adding more red/orange light in the evening – low-level lamps, salt lamps, or firelight – to mimic natural sunset conditions.
Nutrition and cravings
When circadian rhythms are disrupted, hormonal imbalances increase the drive for quick energy. This often shows up as cravings for sugary or starchy foods in the afternoon and evening.
To manage this:
Eat balanced meals with protein, fibre, and healthy fats to keep blood sugar steady.
Front-load carbohydrates earlier in the day when insulin sensitivity is higher.
Have healthy alternatives ready for when cravings strike – for example, oatcakes with hummus or apple slices with nut butter instead of biscuits.
Avoid skipping meals, which worsens cravings later on.
Why circadian rhythm matters
The circadian rhythm is not simply about sleep – it underpins hormone balance, metabolism, immune health, and even cardiovascular risk. When the clocks change and daylight hours shorten, paying closer attention to light exposure, meal timing, and evening habits can prevent energy dips, cravings, and mood changes.
If you struggle with fatigue, cravings, or poor sleep over the winter months, get in touch with me. As a nutritional therapist I can help offer a individual personalised plan that will help you understand what’s driving health issues and support you with strategies tailored to your needs.
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