Sleep deprivation, obesity, and vitamin D deficiency are all linked together

Sleep deprivation, which is widespread, poses a significant risk to both physical and mental health. Research suggests that people with a high BMI are more likely to be vitamin D-deficient, which in turn can affect both body weight and sleep quality. Overall, vitamin D appears to influence sleep quality both directly and indirectly by affecting BMI. This is the conclusion of a large American population study published in Frontiers in Nutrition. The researchers suggest that vitamin D supplementation may improve sleep quality - particularly when it also helps regulate body weight. But how exactly does vitamin D influence sleep and weight? And how much do we really need?

Deep, restorative sleep is essential for the body and mind to recharge and recover for the next day. During sleep, the brain also clears out toxic waste products that build up when we are awake and active. Young adults are generally advised to get 7-9 hours of sleep per night, while older adults should aim for 7-8 hours. Yet, despite these recommendations, 43% of American adults do not get enough sleep and a similar trend is seen across the Western world. Numerous epidemiological studies have linked poor sleep to a range of health problems, including depression, cancer, cardiovascular disease, cognitive decline, accidents, and premature death. Previous studies have shown that vitamin D affects the nervous system and several parameters related to sleep quality. Around one billion people worldwide are estimated to be deficient in vitamin D, with people who are overweight being particularly at risk.
The new study set out to investigate the relationship between vitamin D, body weight, and sleep quality in more detail. The researchers used data from the large American NHANES study, which tracks lifestyle and health in the population over time. The analysis included 20,865 participants, of whom 39% suffered from sleep deprivation. A statistical method called logistic regression was used to assess the link between blood levels of vitamin D and poor sleep. Another method, mediation analysis, was applied to explore the degree to which vitamin D deficiency, sleep deprivation, and obesity might be interconnected.
Overall, the results showed a significant association between low vitamin D levels and sleep deprivation in American adults. The study also shed light on the underlying mechanisms by which vitamin D may regulate sleep. Interestingly, the strongest positive effect of higher vitamin D levels on sleep quality was seen in overweight participants with the lowest BMI in that group. This suggests that vitamin D may help improve sleep quality in people who are overweight by regulating blood sugar and lowering BMI.
The researchers recommend that anyone suffering from both vitamin D deficiency and poor sleep should aim to optimize their vitamin D status through supplementation. Official guidelines typically recommend 5-20 micrograms per day, but these amounts are relatively low, and people who are overweight often need more vitamin D.

• Around one billion people worldwide are deficient in vitamin D
• More than one billion people are severely overweight
• Sleep deprivation is also highly prevalent, and both obesity and vitamin D deficiency may increase the risk
• Optimal blood levels of vitamin D should be above 75 nmol/L (≈ 30 ng/mL)

Vitamin D’s effect on sleep quality and weight

Earlier studies indicate that most brain cells have vitamin D receptors, including areas such as the pineal gland, hypothalamus, substantia nigra, grey matter, and raphe nuclei - all of which play a role in sleep patterns, sleep quality, and muscle relaxation during sleep. Vitamin D also influences sleep by regulating an enzyme (tryptophan hydroxylase) that converts tryptophan into 5-hydroxytryptophan. This compound boosts serotonin production in the brain, which is important for sleep quality.
Overall, vitamin D appears to help regulate the body’s circadian rhythm by activating and controlling specific genes, enzymes, and stem cells. It also plays a role in insulin production in the pancreas, blood sugar regulation, and fat tissue metabolism. Lower vitamin D levels - and changes in the body’s vitamin D receptors (VDR) - have been linked to obesity and higher BMI. Given how common both sleep deprivation and obesity are, more attention should be given to maintaining adequate vitamin D levels, as it supports many functions related to sleep quality and weight management.

Vitamin D blood levels

• Severe deficiency (below 25 nmol/L)
• Deficiency (25-29.9 nmol/L)
• Insufficient (50-74.9 nmol/L)
• Sufficient (above 75 nmol/L)

References:

Boya Gong et al. The mediating effect of BMI in serum vitamin D related sleep deprivation based on the NHANES database. Frontiers in Nutrition 2025