Have you ever moved through winter feeling low, slow, and “off,” without being able to point to a single reason why? You’re sleeping, you’re managing your responsibilities, nothing has gone dramatically wrong — and yet there’s a fog that won’t lift.
At Cogniva Counselling, we hear this often during the colder months. And while emotional wellbeing is always shaped by many things — stress, relationships, life transitions — there’s a physical piece that’s easy to overlook: how much daylight your body is actually getting.
It’s Not Just “Winter Blues” — There’s a Mechanism Behind It
Shorter days don’t just feel different. They change your biology in two distinct ways:
1. Vitamin D production drops. Your skin makes vitamin D when it’s exposed to UVB rays from the sun. In winter, when the sun sits lower in the sky and days are shorter, there’s simply less UVB reaching you — even on a “sunny” day. Low vitamin D has been linked to fatigue and low mood, on top of its better-known roles in immune function and calcium absorption.
2. Light exposure to your eyes affects mood and sleep, separately from vitamin D. This is the mechanism behind what’s commonly called seasonal low mood. Daylight entering your eyes helps regulate your circadian rhythm and your body’s serotonin and melatonin balance. Less daylight, less regulation — which can show up as low energy, disrupted sleep, and that gloomy, foggy feeling that doesn’t seem to have an obvious cause.
Both of these are physiological. Neither means something is “wrong” with you. It means your environment changed, and your body responded the way bodies do.
A Few Things Worth Knowing
- Glass blocks the UVB rays your skin needs. Sitting by a sunny window or in a car doesn’t help your vitamin D levels, even though it feels warm and bright.
- You don’t need much — but you do need consistency. Most guidance suggests somewhere between 10–30 minutes of midday sun on your face and arms, several times a week, depending on your skin tone and the UV index. Darker skin tones generally need longer exposure to produce the same amount of vitamin D.
- Cloudy, overcast daylight still matters for mood and sleep, even when it’s too weak for vitamin D production. Getting outside on a grey day is still worthwhile.
- If you’ve ever lived somewhere with long, dark winters — northern Europe, for example — and noticed this feeling more intensely there, that’s not a coincidence. It’s latitude and physics, not a personal failing.
Quick, Realistic Ways to Get More Light Into Your Day
- Step outside within the first hour of waking, even briefly, even if it’s cloudy.
- Take a short walk around midday rather than only in the early morning or evening.
- Eat a meal outdoors or near an open window with direct airflow (not just behind glass).
- Pair sun exposure with something you already do — a phone call, a coffee, a walk to the shops.
- If your levels are a concern, ask your doctor about testing your vitamin D and whether supplementation makes sense for you specifically. This isn’t a one-size-fits-all answer, and it’s worth getting real numbers rather than guessing.
When It’s More Than Light
Sometimes what feels like winter fog is genuinely tied to the season — and easing once the light changes. But sometimes low mood persists regardless of sunlight, or it’s tangled up with other stressors, grief, or longer-standing patterns. If that’s where you find yourself, that’s exactly the kind of thing worth bringing into a counselling space — not to diagnose yourself from a blog post, but to actually be heard and supported in working out what’s going on.
If you’ve been feeling low, foggy, or simply not yourself lately, you don’t have to figure out why on your own.
