why does being in the sun make you tired?
Questions And Answers

Why Does Sitting in The Sun Make You Tired?

Last Updated on February 17, 2024 by Louise Carter

Prolonged exposure to the sun’s rays can make you feel sluggish and sleep. This is known as sun fatigue, which is sometimes a precursor to heatstroke.

When the skin grows hot due to sun exposure, the blood vessels widen to flush the skin and promote sweating. The body focuses on this task and loses internal fluid through sweat, so you feel tired.

If you haven’t applied sunblock, the skin will burn, further exacerbating the problem. Also, the discomfort associated with sunburn and the skin’s attempts to heal can be exhausting.

If you feel sleepy in the sun, avoid napping because it’ll likely lead to sunburn or other unwanted issues. Instead, find a shaded area because the symptoms of sun fatigue should subside within 30 minutes.

Why Does The Sun Make Me Sleepy?

Spending a day in the sunshine is appealing but frequently leads to sluggishness.

Here are the reasons why being in the sun makes you feel so tired:


Vasodilation occurs when the skin’s blood vessels widen, allowing increased blood flow to the surface. It’s a natural response to sun exposure because it encourages the skin to flush and sweat to cool off.

While blood is redirected to the skin, the rest of your body has limited resources. This means the heart will likely slow down during vasodilation, which the body associates with sleep.

Unfortunately, the longer vasodilation continues, the more weary you’ll feel.

The body works hard to prevent overheating, but focusing on the skin leaves you increasingly exhausted as the rest of your organs and muscles must compensate.

How do you deal with sun fatigue?


When our core body temperature rises above a comfortable level, the nervous system sends messages to the sweat glands to release fluid and cool the skin down.

This means you’ll lose fluid from within your body. If this fluid isn’t replaced, dehydration becomes increasingly likely. When the human body is dehydrated, it ceases to fully function.

The mind will feel this impact as much as the body, leaving you foggy-headed, dizzy, and exhausted.


If you spend time in the sun without sunblock or use a product that offers insufficient protection due to a low SPF, your skin is almost certain to burn.

This will leave you tired and sleepy. Everybody has experienced sunburn at least once, so you’ll know it leaves the skin feeling hot.

The body will react to this, as established during the section on vasodilation.

Additionally, sunburn can be extremely uncomfortable. Any time an article of clothing or another person brushes against the impacted skin, you’ll feel a searing soreness.

Sunburn can also lead to a constant, chronic throbbing pain on the skin until it heals.

The body will attempt to repair the skin, likely culminating in peeling and new skin growth. This process can be tiring, with Clinical Medicine stating that pain and fatigue are often intertwined.

Vitamin D

Does vitamin D from the sun make you sleepy? According to Sleep Medicine, the same part of the brain regulates vitamin D intake and sleep cycles.

While the sun’s brightness activates your circadian rhythms and convinces the body and mind it’s time to be alert, organic fatigue will settle over time. The body can’t overdose on vitamin D.

Why Does the Sun Make My Eyes Tired?

Spending time in the sun can leave the eyes tired and sore. This may be due to ocular dryness if you haven’t been diagnosed with a medical condition that suggests light sensitivity.

A study concerning dry eye patients published in the Indian Journal of Ophthalmology found that farmers, outdoor laborers, and people living in rural settings were likelier to experience this issue.

The more time you spend in the sun, the likelier your eyes will dry out and experience pain, irritation, and fatigue. If you fail to shield and protect your eyes, you risk photokeratitis (sunburn of the eye).

Wear quality sunglasses to protect your eyes if you plan to spend an entire day in the sun. Lenses should block 100% of UVA and UVB light. Polarized glasses provide the most protection.

What is Sun Fatigue?

Sun fatigue (heat exhaustion) involves symptoms that arise when you spend too much time in direct sunlight. Sun fatigue isn’t necessarily dangerous if you act immediately to cool off.

If you ignore the warnings your body is sending, you’re at risk of heatstroke. Beyond feeling increasingly tired and sleepy, common sun fatigue symptoms include the following.

  • Headaches that can lead to dizzy spells.
  • Nausea and stomach cramps, potentially leading to vomiting.
  • Skin feeling clammy to the touch despite the heat.
  • Muscles start cramping and growing increasingly weak.
  • Increase in heart rate, potentially leading to rapid, shallow breathing.
  • Chronic thirst, no matter how much water you drink.

You must react to sun fatigue without delay.

How Do You Deal with Sun Fatigue?

If you feel sleepy in the sun and fatigue sets in, don’t be fooled into thinking that a quick nap will resolve the issue. Your skin will likely burn, and you may develop heatstroke.

At the first sign of sun fatigue symptoms, seek shade from direct sunlight. Ask somebody to accompany you if your symptoms worsen, as you may need medical assistance.

Find somewhere to sit and relax, loosen tight-fitting clothing to allow the skin to breathe, and sip on water. While guzzling water is tempting, regular sipping will regulate your body temperature.

Sun fatigue symptoms should pass in around 30 minutes. Then, apply suitable sunscreen.

How Not to Get Tired in the Sun

Having established that sun fatigue can be problematic, you’ll be keen to avoid growing too tired in the sun. Equally, you must protect your mind and body if you work outdoors.

Seek Shade

Find a shady spot you can occasionally retreat to escape the sun’s rays. Also, wear a baseball cap or other headwear to keep the sun off your head, face, and eyes.

Above all else, listen to your body. If you feel weak or tired, it’s time to take a break from the sunshine.

Regularly Hydrate

Regularly hydrate, replacing any fluid your body loses through sweat. Water is the simplest solution, but consider drinks high in electrolytes.

Gatorade and similar drinks will meet this need, but coconut water contains far less sugar. Drinking coconut water keeps the heart rate steady, quenches thirst, and hydrates the body and mind.

Avoid binging on energy drinks to fight off sluggishness caused by the sun because caffeine is a diuretic. Excessive caffeine means you’ll need to urinate more, which could lead to dehydration.

why does the sun make me sleepy?

Avoid Heavy Foods

While hot weather is often associated with heavy foods like barbecued meat, remember what you eat when spending a day in the sun. Consume lighter snacks rather than large meals.

Denser foods take longer to digest and require more input from the body. This means energy will be expended on digestion that could have been used to cool you down.

White meat and fresh seafood are easier for the body to digest, and fresh fruit will stave off dehydration as it’ll often be filled with water. Watermelon is among the most hydrating snacks for a sunny day.

Periodically Reduce Your Body Temperature

If you can reduce your temperature, your body won’t need to exert itself.

If you enjoy a sunshine break or vacation at a hotel or on the beach, you should have access to water. A brief dip in the pool or ocean is a simple way to cool off and regulate your body temperature.

If not, keep a washcloth handy and occasionally douse it with cool water. Dab this on your skin, especially any areas you feel particularly hot.

Aloe vera will also have a cooling and calming effect on the skin. BMC Complementary Medicine and Therapies stated that aloe prevents a rise in body temperature.

Feeling sluggish and sleepy during intense sunlight is to be expected. Plan accordingly if you wish to spend a day outside in sunny weather, ensuring you don’t fall foul to sun fatigue.