The Winter Mood Dip: Seasonal Low Mood, Vitamin D, and Practical Ways to Feel Better

Dec 18, 2025 Vitamins and Supplements

When winter arrives, many people notice a shift in their energy, motivation and overall mood. Shorter days, colder temperatures and reduced sunlight can combine to create real physical and emotional challenges. Two issues that often appear side by side are Seasonal Affective Disorder (SAD) and low vitamin D levels. These concerns can overlap and make each other feel worse, but there are practical steps that can help.

This guide explains how daylight changes affect your mental wellbeing, why winter sunlight is not enough to maintain vitamin D levels, and how supporting your body nutritionally can make a difference.

You can also read our recently updated winter guide, Essential Winter Vitamins: Vitamin D3, The Sunshine Vitamin, on our blog.
 

Daylight Changes and How Your Mood and Natural Sleep Cycle Can Suffer

During winter, the UK receives far fewer hours of daylight than in summer. This reduction affects the body’s circadian rhythm, which regulates sleep, hormone balance and alertness. Less light exposure can lower serotonin levels, a chemical linked with mood regulation and feelings of well-being. At the same time, melatonin can increase, leaving you feeling sleepier, less motivated and more withdrawn.

While everyone is different, for many people these changes lead to noticeable shifts in mood. You may feel more fatigued, crave carbohydrates or find it harder to stay focused. These symptoms are common during the darker months but can be more intense for those experiencing SAD (Seasonal Affective Disorder).

How the Lack of Sunlight Affects Your Vitamin D Levels

Vitamin D is produced naturally when sunlight hits the skin. From October to early spring, the sunlight in the UK is not strong enough for most people to produce sufficient vitamin D. Over time, this can lead to low levels, which may cause tiredness, muscle weakness and reduced immune function.

The NHS suggests considering a daily vitamin D supplement during autumn and winter.

Maintaining good vitamin D levels is not only important for bone and muscle health. It also plays a role in immune support and overall energy. When vitamin D becomes depleted, your body can feel the effects quickly.

SAD: A Mood Disorder

Seasonal Affective Disorder is a type of depression that appears seasonally, most often in winter. This is more than what some consider the usual “winter blues”. Symptoms can include persistent low mood, lack of pleasure in daily activities, irritability, concentration problems, low energy and increased need for sleep.

Although SAD is triggered by reduced daylight, several factors can contribute. Low vitamin D is not considered a direct cause, but research suggests that insufficient levels may influence the severity of symptoms.

Low Vitamin D Can Make SAD Feel Heavier

Low vitamin D is known to affect energy levels and immune health. When combined with the natural mood changes triggered by darker days, the overall impact can feel more intense. Many people report that when their vitamin D levels are supported, their mood feels more stable through winter.

Addressing low vitamin D is not a cure for SAD, but it can be a valuable part of a wider winter wellbeing routine that includes daylight exposure, movement and emotional support.

Practical Steps to Support Mood and Vitamin D Levels This Winter

• Seek daylight where possible -A short walk during daylight hours can help reset the body clock and support serotonin production.
• Use a light therapy lamp if helpful - Many people with SAD benefit from bright light therapy, which mimics natural daylight.
• Stay active - Even gentle daily movement boosts endorphins and supports energy levels.
• Consider vitamin D supplements - Supplements can help maintain healthy levels when sunlight is limited.

Vitamin D and Winter Support Options at Simply Meds Online 

Below are several high-quality options available at Simply Meds Online, chosen for the way they support your energy, mood, and nutritional needs during the winter months.

Hinnao Vitamin D3 and K2

This Hinnao liquid supplement combines vitamin D3 with vitamin K2, which helps ensure that calcium is directed to bones rather than soft tissues. The finely blended, fast-absorbing formula promotes fast and efficient absorption. Hinnao Vitamin D3 and K2 is ideal for those wanting an easy-to-use, premium vitamin D option that supports bone strength and cardiovascular health.

Almus Turmeric 1000 mg and Vitamin D

Turmeric is traditionally known for its antioxidant and joint support properties and is often used in modern products due to how well it works. Almus Turmeric 1000mg and Vitamin D pairs high-strength turmeric with vitamin D for combined bone, muscle and immune support. It is suitable for anyone looking to maintain mobility and general well-being during winter.

SunVit D3 Vegan Range  1000 IU

This vegan-friendly vitamin D3 is sourced from lichen, making it ideal for those who avoid animal products. SunVit D3 Vegan provides 1000 IU per tablet, which supports bone health, immunity and normal muscle function throughout winter.

Almus Glucosamine Sulphate 500 mg with Vitamin C 

Glucosamine supports joint health and movement, and vitamin C contributes to collagen formation for healthy cartilage. This combined Almus Glucosamine and Vitamin C formula is great for those active throughout winter or anyone who wants to maintain joint comfort.

ProVen Probiotics for Adults - 25 Billion Live Friendly Bacteria for Digestive and Immune Support

This advanced ProVen probiotic provides 25 billion friendly bacteria along with vitamin D3, zinc, vitamin C and selenium. The combined nutrients support both immunity and digestive balance, which are important for winter wellbeing. It is a convenient all-in-one option for those looking to support their body from multiple angles.

Simply Meds Online: Supporting You Throughout the Darker Months

Winter often brings genuine changes to mood and physical health, but understanding how daylight and vitamin D interact can help you manage the season more comfortably. Supporting your body with light exposure, movement and nutritional supplementation can make a real difference. Here at Simply Meds Online, we only stock products from trusted brands and suppliers and ship directly to your chosen address. This makes staying on top of your winter health easier than ever.

If you are struggling with your mood or mental health more than usual, please speak to your GP or other healthcare provider.