Vitamin D, sun exposure and sleep

Why is sleep important?

Quality sleep is essential to our health and well-being. It allows our bodies and minds time to rest and recharge. In general, sleep plays a role in maintaining physical and mental health and the immune system. Unfortunately, many of us don’t get the enough quality sleep we need to improve our health and wake up feeling refreshed. Lack of sleep is linked to many chronic health problems including high blood pressure, obesity, depression, kidney disease and heart disease.

Does vitamin D help with sleep?

Vitamin D is often on the list of sleep aids — and for good reason! Multiple observational studies, with more than 2,000 participants involved, saw a significant association between lower vitamin D levels and shorter sleep duration. This is important given that vitamin D deficiency is a global concern as up to 70% of the world’s population has low levels of vitamin D.

While sleep is affected by a variety of factors, recent research suggests that vitamin D deficiency is linked to poor sleep including sleeping less and poorer sleep quality. Associations have also been found between low vitamin D and daytime sleepiness and an increase in the time it takes to fall asleep at night. 

There are several potential mechanisms by which vitamin D may affect sleep. Studies have found receptors for vitamin D in parts of the brain involved in regulating sleep, including the areas of the brain responsible for the early stages of falling asleep and staying asleep. Vitamin D has also been shown to play a role in the synthesis of melatonin, a hormone responsible for helping us sleep. 

Does Vitamin D improve sleep quality?

A variety of studies have shown that increasing vitamin D levels can improve measures of healthy sleep.  

One study of chronic pain patients with difficulty sleeping found that lower levels of vitamin D were associated with worse sleep difficulties. With vitamin D supplementation of 1,200 IU per day, these patients noted a significant improvement in their time to sleep, sleep efficacy, and an average of an additional 45 minutes of sleep each night.

A randomized clinical trial that looked at patients with sleep disturbances found that taking a vitamin D supplement improved sleep as measured by the Pittsburgh Sleep Quality Index (PSQI). PSQI is a survey that assesses sleep quality and pattern. This study also found that taking vitamin D supplements reduces the time it takes to fall asleep and increases the time people spend falling asleep.

Does vitamin D help in sleep disorders?

The researchers also suggested a possible link between vitamin D deficiency and sleep disorders such as sleep apnea. Both vitamin D deficiency and sleep apnea are associated with obesity, inflammation, and impaired glucose metabolism. One study that looked at individuals with sleep apnea found that those with obstructive sleep apnea had significantly lower vitamin D levels than people without sleep apnea, and that low vitamin D levels was associated with severe sleep apnea. While more research needs to be done on the mechanism of how vitamin D affects sleep disturbances, some researchers have suggested that the link may be due to the role that vitamin D plays in managing inflammation in the body. 

How does exposure to sunlight affect the circadian rhythm? 

In addition to producing vitamin D, exposure to sunlight regulates other processes in the body that affect sleep. Sun exposure plays an important role in regulating the circadian rhythm. Circadian rhythm is the body’s internal time clock that regulates our sleep-wake cycle and determines how long we sleep. When light enters the eye, it signals to the body that it is time to wake up. When it gets dark at night, the levels of melatonin in the body increase, making us feel sleepy. Since melatonin levels are controlled by exposure to light, exposure to sunlight plays an important role in regulating sleep time.

Exposure to light, even artificial light, before trying to sleep can disrupt the sleep-wake cycle and can result in less and less sleep. To improve sleep quality, it is best to ensure that the sleep cycle is regulated by getting light in the morning when you wake up and avoiding light as much as possible at night before bed.

How Much Vitamin D Should You Take for Sleep?

Vitamin D is not a “one-size-fits-all” approach, and while there is no one-size-fits-all amount of vitamin D, experts agree that maintaining adequate levels of vitamin D is broadly important to health. An adequate vitamin D level is usually considered to be above 30 ng/ml.  

Among the medical community, there is debate about the best way to get vitamin D. Some doctors recommend oral supplements, but there are a variety of reasons why taking vitamin D may not be the best option. Oral vitamin D supplements are not effective for a surprisingly large number of people, and they do not offer the same health benefits as exposure to light. To find out more about this topic,

Getting vitamin D from light allows your body to self-regulate vitamin D production and achieve what your body needs to stay healthy, without the risk of overdose or toxicity. Unlike oral supplements, you cannot overdose on the vitamin D that your skin produces. If you have enough vitamin D, your body will produce less.