Why Do Dogs Lay in The Sun?

It’s almost a guarantee that at some point you’ve found your dog snoozing in a warm spot on the floor, laying in the sunlight shining in through a nearby window. You’ve maybe even caught them inching around the room to soak up every bit of the sun’s warm rays as it moves across the sky. You’ve also probably seen your pup take up prime position in the back garden on a warm summer’s day, laying directly in the hot sun to take a nap. 

Any responsible dog owner knows that dogs can get uncomfortable in the heat and they’re very prone to overheating, so why do our dogs like to lay in the sun?

In short, just like humans, dogs use sunlight as a source of vitamin D. Sunlight has been found to have an anti-bacterial effect on dogs, and it helps them to fight off diseases. It also produces serotonin, which helps dogs and humans alike to feel more attentive, happy, and relaxed. 

The science behind why dogs like to lay in the sun

To put it simply, dogs enjoy laying in the sun because it feels good. But delving a little deeper, there are biological reasons that explain the sun-worshipping behaviour from a more scientific point of view. 

Just like humans, dogs use sunlight to metabolise particular fats and oils in their body into Vitamin D. But differently to us, dogs get almost no Vitamin D directly from sunlight hitting their skin, so they have to derive the majority of their intake from their diet. 

How do dogs absorb Vitamin D from sunlight?

To understand how this process works in dogs, we can first investigate how our human bodies create the Vitamin D that we need. When we’re exposed to the sun, its rays play a part in breaking down the oils in our skin that create Vitamin D. The oil in our skin reacts to the UV rays from the sun, which breaks down the chemical bonds and results in the creation of Vitamin D3. After the vitamin is broken down, the body absorbs it back into our bloodstream through a process called dermal absorption, which takes around 15 to 20 minutes. 

While human’s bodies form Vitamin D in the skin where it is directly absorbed into our system, dogs have a layer of fur that makes it difficult for them to absorb this vitamin in the same way as us. If that’s so, then how do dogs absorb Vitamin D? Well, they don’t – instead, our pups will form the vitamin on their fur where their fats and oils get deposited. They then ingest the Vitamin D into their system by grooming themselves and licking their fur, functioning in a similar way to a human taking a dietary supplement tablet. 

The Vitamin D is then absorbed by their intestines, and enzymes in their liver change it to a slightly different molecule, which is finally metabolized by their kidneys back into an active form of Vitamin D. This form of Vitamin D is actually a hormone called ‘calcitriol’, and is 

stored mainly in the dog’s fatty tissue to be used in their body later.

Why do dogs need Vitamin D?

In humans, dogs, and all other mammals, Vitamin D plays an essential role in the body’s use of minerals, and encourages the production and maintenance of bones by managing the body’s use of phosphate and calcium. Vitamin D is actually considered to be a ‘pro-hormone’ as it functions more like a hormone than a vitamin in these ways.

Our dogs need Vitamin D in order to grow and maintain strong bones and healthy joints, and it plays an essential role in maintaining the proper functioning of dogs’ nerves and muscles. It is partially responsible for controlling inflammation in the dog’s body, and new research suggests that Vitamin D also has an effect on the regulation of their genes and the maintenance of their cell health. 

Image Credit iStock.com/damedeeso

The different reasons why your dog likes to lay in the sun

Now we know the science behind the behaviour, we can explore some of the other reasons why your dog might seek out a warm patch of sunlight for their afternoon nap:

Rest and Relaxation

It might seem obvious, but the same is true for dogs as it is for humans – we all need to have a little rest from time to time, and doing this in the sun can be a particularly enjoyable experience. 

I’m sure you can recall a moment in your life (most likely a few) when you’ve caught yourself dozing off in a sunny spot. So, dogs will do the exact same thing. They will seek out sunlight to lay and sleep in as it makes them feel restful and relaxed, just like it does for us.


Another reason that can be said for us too, is that dogs enjoy feeling the warm sensation of the sun’s rays on their body. 

It is in dogs’ nature to seek out warmth to make them feel safe. They associate the feeling of warmth with being in a secure enclosed space, a trait leftover from their evolutionary days, so they enjoy laying in the warmth of the sun to give them that sense of safety.

On top of this, your dog will lay in the sun because doing so helps to regulate its body temperature, which is particularly important for them in the cooler months. 

Sunlight and warmth will also help older dogs or dogs that suffer from joint pain, as it helps to lessen the pain by increasing the production of endorphins in the dog’s brain. So, it’s a good idea to encourage older dogs or dogs that suffer from this pain to spend some time in the sun, as it will help make your dog feel happier and pain free. 


Again, just as it is for humans, being in sunlight is believed to increase the levels of serotonin in dogs’ brains. 

Serotonin is known as the ‘happy hormone’, as it is a hormone produced by our brains that makes us feel relaxed and emotionally stabilized. Serotonin is equally as important in dogs’ brains as it is in ours, being vital for the regulation of their body temperature, behaviour, appetite, pain awareness, and for the functionality of their hearts and lungs.

An additional benefit of serotonin is that the hormone has also been linked to a decrease in aggression in dogs, improving their overall temperament. Take note of how relaxed your pup seems next time they wake up after a nap in the sun!

Skin Health

Sunlight has also been found to have an antibacterial effect on dogs’ skin, keeping it clean and healthy. 

UV light in the sun’s rays can kill unwanted bacteria and yeast that grows in wounds on the surface of your dog’s body. Anaerobic bacteria thrive in dark and damp conditions, so direct sunlight helps to dry out dogs’ wounds and destroys microscopic fungi on their skin. This stops the bacteria from multiplying and spreading, which could cause your dog to suffer from some nasty health complications.

Making sure that your dog gets enough sun

Laying in the sun is a natural instinct for our dogs, so most of the time they’ll inherently know how much they need. With that said, it’s always best to keep an eye on them to make sure that they’re getting just the right amount of sunlight in order to gain its health benefits, while also protecting them from the dangerous consequences of overexposure. 

How much sun does a dog need daily?

You might find conflicting numbers when searching for exactly how long you should let your dog lay in the sun, but most experts recommend that they get around 20 to 30 minutes of direct exposure twice per day. It is recommended for larger breeds to spend a little longer in the sun, for periods of around 40 minutes twice per day. 

The time of day when your dog is exposed to the sun is also an important factor to be considered. The amount and type of sunlight that your dog gets will affect their sleep cycle, also known as their ‘circadian rhythm’, which is regulated by UV and UVB light. As the sun produces varying levels of UV and UVB light throughout different parts of the day, you should let your dog out for their first dose of sunlight in the morning, a short burst in the middle of the day, and their final dose in the afternoon or evening. 

Your dog should be outdoors when they’re getting their daily quota of sunshine, as opposed to getting it from sunlight coming through a window. This is down to the fact that glass and plastic absorb the majority of ultraviolet rays, which prevents them from reaching your dog. Even though it may feel just as good to them, they’re missing out on all of the health benefits that only come from being under the actual UV rays. 

So, it’s a good idea to encourage them to go out and have a rest in the yard, even if it’s in the shade – the sun’s reflective rays will still reach their body as long as they’re outdoors. However, this might be easier said than done if you’re the owner of a housebound dog. In these circumstances, it’s recommended that you swap out fluorescent or incandescent bulbs with ‘full-spectrum’ lighting, which can be readily purchased at most hardware stores. Install the bulbs and keep them lit during the day in areas where your dog spends a lot of time, such as near their food bowl or their bed. 

Encouraging your dog to lay in the sun

It is in their natural instincts to seek out sunlight, so your dog will most likely manage to get all of the exposure they need on their own. You can do some things to facilitate this, such as making sure your pup has a space that’s safe and enclosed (such as a back yard or sunny outdoor space), giving them access to a cool, shady spot in case they become overheated, and encouraging them to drink lots of clean, fresh water so they can cool down and stay hydrated. It is just as important to keep an eye on them and provide them with a nearby escape from the heat and sun as it is to encourage them to soak up its rays.

The dangers of your dog getting too much sun

Unfortunately, dogs are just as susceptible to the negative effects of getting too much sun on their bodies as we humans are. They are actually able to get a tan, become sunburnt, and can even get severe sunstroke, despite their layer of fur. Dogs with black fur are more prone to overheating, while dogs with white fur or short coats are at a particular risk of getting sunburnt. 

Some of the health problems that your dog might suffer from as a result of too much sun exposure can include: 

Heat Exhaustion

When we get too hot, our bodies are designed to regulate our temperature by sweating. Dogs are unable to sweat, so instead, they will pant to lower their body temperature. Even though they have their own methods of cooling off, they’re very susceptible to overheating, especially when they’re laying in the sun on a hot day. 

Keep checking to see if your dog is extremely thirsty, panting excessively, drooling, lethargic, dizzy, or experiencing muscle tremors, vomiting or diarrhea, as these are all signs of heat exhaustion.

Heat Stroke

Heat stroke is the next stage after heat exhaustion. Dogs will suffer from heat stroke if their body temperature reaches 106°F (41°C) or more. This is a very serious condition that is caused by your dog’s inability to cool itself down as it becomes too overwhelmed by the effects of the heat. After they lose the ability to cool off, other parts of their internal system will start to fail too, such as their circulatory and neurological systems. 

If your dog is vomiting or having diarrhea, walking unevenly, having seizures, or collapsing and becoming unresponsive, then they are likely suffering from heat stroke.

Skin Cancer

They may have a layer of partially protective fur, but dogs are still very much at risk of developing skin cancer from excessive exposure to sunlight. There are a few different types of skin cancer that can affect dogs, and certain breeds are more at risk of skin cancer than others. For instance, Dobermans, Miniature Schnauzers and Scottish Terriers seem to be mainly affected by benign melanomas, while Collies, Beagles, and Basset Hounds tend to suffer from the more severe squamous cell carcinoma.

Look out for unusual patches on your dog’s skin that may appear raised or colored, as well as warts or inflamed patches.

For Happy Dogs Team

Our team are a group of dog lovers who strive to give our four-legged friends the best lives possible. We bring together lists of the best dog services in your local area - along with tips, guides and product reviews. Everything you need for happy dogs!

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