As winter sets in and the daylight hours shrink, the conversation around vitamin D becomes especially important. Beyond its well-known role in supporting bones, new research shows that vitamin D may also influence mood, sleep quality, brain health, and inflammation.
Vitamin D and the Brain
Researchers are increasingly interested in how vitamin D interacts with the brain’s hormonal systems. It helps regulate serotonin and melatonin — two key chemicals involved in emotional wellbeing and the sleep–wake cycle. Because of this, low vitamin D levels may contribute to low mood, disrupted sleep, and decreased energy.
Vitamin D and Sleep
Sleep studies are still emerging, but early evidence shows a clear pattern. Low vitamin D status may be linked with poorer sleep quality, shorter sleep duration, and increased daytime tiredness. Many people notice that their sleep becomes lighter or more broken during the darker months.
A Topic Close to My Heart
Stepping away from sleep for a moment , there is another subject that is deeply meaningful to me – the possible connection between vitamin D deficiency and dementia.
Sadly, like so many others, my family have been affected by this heartbreaking condition. This makes me feel compelled to share well-studied research that may offer even a small benefit to others.
Vitamin D and Dementia Risk
One of the most striking areas of new research focuses on vitamin D and long- term cognitive health. Over the last 12 months, several important studies have emerged exploring the role of vitamin D in cognitive health. Over the last 12 months , several important studies have explored this link.
One study found that people with higher vitamin D levels had better memory, improved cognitive function, and a significantly reduced risk of developing dementia. Other research suggests that maintaining adequate vitamin D may help slow cognitive decline in older adults, making it an increasingly important nutrient for long-term brain health.
The University of South Australia Study
A major genetic study from the University of South Australia, analysed data from nearly 300,000 UK participants, reported that :
• People with low vitamin D levels had smaller brain volumes
• Vitamin D deficiency was linked to an increased risk of dementia and stroke
• Genetic analysis suggests a causal relationship between low vitamin D and dementia.
• Up to 17% of dementia cases in the UK might have been preventable if vitamin D levels had been maintained within a healthy range.
Researchers concluded that correcting low vitamin D levels may help reduce chronic inflammation — an increasingly important area in both physical and mental health.
What Healthy Vitamin D Levels May Support
Although research is ongoing, current evidence suggests that maintaining healthy vitamin D levels may support:
• improved mood
• better sleep
• healthier brain ageing
• reduced inflammation
These findings are particularly meaningful considering how many families are touched by dementia. Vitamin D is not a cure, but supporting healthy levels may be a simple, accessible step in protecting cognitive wellbeing as we age.
Winter and Vitamin D Deficiency.
With deficiency particularly common in winter, it may be beneficial for many people — especially in the UK — to check their vitamin D status or consider supplementation.