With a cacophony of health supplements readily available, it is difficult to know which, if any, of these to take. Once you do decide what to invest in, do you know how it will affect you? Will it make you feel sluggish or hyper? Will you struggle to sleep or will it help with sleep? Vitamin D is one of those supplements that have some contention around whether they are necessary or beneficial. But are you getting enough? And how can getting too little affect your sleep?

About Vitamin D

According to the Mayo Clinic, vitamin D is essential in helping your body absorb calcium. Your body creates it by using direct sunlight to convert a chemical on your skin into calciferol (the active form of the vitamin D3). Sadly, vitamin D is only found in a few foods. Depending on the season, amount of time spent outside, and time of day, many people can become vitamin D deficient. This deficiency can range from mild to severe and affects several aspects of the body.

What Happens When You Don’t Get Enough Vitamin D?

Without enough of this vitamin, your bones can become soft and brittle. This can cause a whole host of health issues such as osteoporosis or multiple sclerosis. Though more studies need to be done, there is also a link between vitamin D deficiency and patients with multiple myeloma, prostate cancer, and ovarian cancer. For young children and babies, vitamin D deficiency can lead to rickets: a skeletal-muscular condition that affects normal bone shape and growth. Because vitamin D does not pass through breastmilk, breastfed babies not yet eating solids are most at risk for rickets. For this reason, the American Academy of Pediatrics recommends a vitamin D supplement for primarily breastfed babies.

The recommended daily dosage, according to the Mayo Clinic, is 400 international units (IU) for infants up to 12 months, 600 IU for those ages 1 to 70, and 800 IU for those over 70. Ensuring you have the recommended amount daily—whether by food, sunlight, or supplementation—is crucial to your skeletal health.

If you ask Yale Medicine, just a few minutes outside (do not forget the sunscreen) can help your body generate plenty of vitamin D. Also be sure to eat foods naturally rich in vitamin D to ensure you are taking in enough. Some of these foods are egg yolks, and fish like tuna and salmon. Some foods are fortified with it, like milk and some cereals. With some sunlight exposure and a varied diet, the vast majority of people do not need to be concerned about a severe deficiency. However, if you stay indoors most of the time and do not regularly consume vitamin D-rich foods—we like fish—taking a supplement may be needed. Ask your doctor about getting blood work done to check your vitamin D levels and decide the appropriate treatment.

Effects on Sleep

Not only is sufficient vitamin D essential for your body, but it is also essential for sleep. In a sleep study published in 2018, it was discovered that the subjects with a vitamin D deficiency were more likely to experience sleep disorders, like insomnia. And the sleep that these patients did get was low-quality sleep. Unsurprisingly, these patients also experienced excessive daytime drowsiness due to the disrupted, low-quality sleep.

While adequate vitamin D intake is crucial for sleep health, how you get it matters, too. It is possible to absorb enough while staying indoors (supplements may be necessary in colder, darker geographical locations). But it may not be the best choice for your sleep. Absorption through sunlight has several benefits.

Here Comes the Sun

Sunlight and sleep are a surprising match: one really aides the other. While sunlight is the best source of vitamin D, it also greatly benefits your sleep. When you get ample sunlight during the day, it helps with setting your biological clock, or circadian rhythm. The Centers for Disease Control and Prevention (CDC) reports that the light and dark cycle of the sun has a powerful effect on your sleep cycle. Darkness causes sleepiness, and bright light causes wakefulness. You can even use this knowledge to manipulate your sleep times. For example, if you need to wake up earlier, eat your breakfast by a window so the sun can assist with waking you up.

Not getting enough sunlight can throw your circadian rhythm for a loop. Staying indoors with artificial lighting and screens can confuse your biological clock, causing you to stay up too late, have trouble falling asleep, or get poor sleep when you finally do. So getting outside for even just a short break every day, and turning those cell phones off at night, will help your circadian rhythm fall into a biologically normal pattern of being up with the sun and sleeping when it is dark. All of this while getting adequate vitamin D and helping both your bones and your sleep.

In Conclusion

By eating a healthy diet with fatty, vitamin D–rich foods, and spending some time outdoors, you will likely have enough vitamin D. Getting an adequate amount will not only help you maintain strong bones, it will also help you sleep better and keep your circadian rhythm on track. All thanks to the sunlight. A healthy lifestyle during your waking hours positively affects your sleeping hours, too!