How Sunlight May Help or Harm Your Headaches

A sunny day usually brings warmth and cheer. But it can also bring on headaches if precautions are not taken. Let's take a closer look at how those beautiful sunshine rays may either help or harm your headaches.

Sunlight

Sunlight itself has been reported to be a migraine trigger. In a 2019 study published in IP Indian Journal of Neurosciences Studies, more than 40% of participants reported bright sunlight as a trigger factor for headache.

Other studies show that just a few minutes of bright light may be a trigger factor for a migraine attack in those who are susceptible. In one case series published in European Neurology, people with a history of migraines from a medical clinic in Turkey developed migraines after being exposed to sunlight. On average, the patients developed a migraine five to 10 minutes after sunlight exposure in the summer and after 60 minutes of sunlight in the winter.

Dehydration

If your body is deprived of water, you can develop a migraine or a dehydration headache, which resembles a tension headache.

So while you may lavish in the warmth of the sun on a summer Saturday, it's critical to drink ample amounts of water—at least 6 to 8 glasses daily (and more if you are exerting yourself and/or sweating).

Heat-Related Illness

Being exposed to the heat of the sun can be dangerous.

There are two types of heat-related illnesses:

• Heat exhaustion
• Heatstroke

Heatstroke is a medical emergency that involves hyperthermia and neurological abnormalities, like seizures or problems with coordination.

Both heatstroke and heat exhaustion are associated with a headache, even though a headache specifically related to heat exposure is not classified or coded on its own by the International Headache Society.

Also, heat exposure may be a specific trigger for new daily persistent headache, which means your episodic or once-in-awhile headache could transform into a chronic, everyday one. 

All that said, if you plan on being out in the sun, please hydrate and find some shade. Of course, if you or someone near you has any signs of a heatstroke, please get emergent medical attention by calling 911.

How Vitamin D May Help

Ultraviolet light from the sun is an important source of vitamin D. While there are a number of reasons why people may be deficient in vitamin D, being exposed to low levels of sunlight is one.

With that, you may be surprised to learn that vitamin D deficiency may be linked to headaches, both migraines and tension-type headaches. However, the underlying physiological mechanism is still unclear. Nonetheless, studies show that vitamin D supplementation (in those with vitamin D deficiency) may potentially reduce the frequency, severity, and/or duration of headaches—particularly migraines.

Remember, a link or an association does not mean that one causes the other. Larger, randomized controlled studies looking at the relationship between vitamin D deficiency and headaches would be helpful.

Lastly, while the sun is an excellent source of vitamin D, please speak to your healthcare provider about the best and safest source of vitamin D for you if you are deficient. Getting too much sunlight can be dangerous, especially since it increases your risk of skin cancer. A vitamin D supplement may be recommended if you can't get enough from diet alone.

A Word From Verywell

While many of us look forward to the warmth and relaxation of long summer days, please be mindful of the heat and its potential for harm.

Wear sunscreen, keep cool, and drink plenty of water. It's a good idea, as well, to speak with your healthcare provider about how to further protect yourself from the heat, especially if you are prone to headaches.