Vitamin D and sunlight: UVA vs UVB, sunbeds, serotonin

As daylight hours shorten and temperatures drop, our skin’s natural ability to make vitamin D also declines. Many people notice lower energy, mood changes, and increased susceptibility to colds during winter; all signs that sunlight exposure and vitamin D production are falling below optimal levels.

This article explains how sunlight creates vitamin D, the key differences between UVA and UVB rays, why sunbeds aren’t a safe substitute, and how nutrients like Vitamin D, Bio-E Vitamin, and AlliTech Capsules help maintain immunity, mood, and wellbeing through the darker months.

UVA vs UVB: What’s the Difference?

Sunlight contains two main types of ultraviolet rays: UVA and UVB. UVA rays penetrate more deeply into the skin and are primarily responsible for tanning and ageing effects. UVB rays interact with cholesterol in the skin to produce vitamin D 3 (cholecalciferol) — the active form your body converts for immune and bone health.

During winter in northern latitudes, the sun’s angle means UVB intensity is too low for vitamin D synthesis, even on bright days. Glass windows, sunscreen, and clothing also block UVB, so short, direct exposure on face and forearms in warmer months is ideal for topping up stores.

Sunlight, Serotonin & Seasonal Mood

Light exposure doesn’t just make vitamin D — it also influences mood. Bright morning light triggers serotonin release, helping regulate focus and positivity. Low light can reduce serotonin and melatonin balance, contributing to “winter blues.”

Supplements such as Vitamin D support this rhythm by maintaining hormone and neurotransmitter balance. Paired with omega-rich and antioxidant nutrients like Bio-E Vitamin, they protect brain and nerve cells from oxidative stress, supporting overall vitality when daylight is limited.

Are Sunbeds a Safe Source of Vitamin D?

Sunbeds emit mainly UVA, not UVB, so they generate little or no vitamin D while increasing risks of skin ageing and DNA damage. Health authorities advise against using them for vitamin D production.

For those with low winter exposure, diet and supplementation remain the safest and most reliable options for maintaining adequate vitamin D levels.

Supplementing Through Winter

The NHS recommends a daily supplement containing 10 µg (400 IU) vitamin D from October to March for most adults. Some individuals may benefit from higher levels under professional supervision.

Dulwich Health Vitamin D provides vegan, easy-to-absorb D3 to maintain immunity, bone strength, and mood stability. Combine it with Bio-E Vitamin for antioxidant protection and AlliTech Capsules to support immune resilience throughout the cold season.

Winter Defence Made Simple

This December, focus on consistent, evidence-based immune care — not quick fixes. The combination of AlliTech, Bio-E Vitamin and Vitamin D delivers daily defence across three fronts: antimicrobial protection, antioxidant repair, and vitamin D balance. Simple, safe, and effective for pre-Christmas wellbeing.