May 24, 2025, 8:49 am | Read time: 4 minutes
Cats are true sun worshippers. When a sunbeam streams through the window, you can be sure it won’t be long before the cat is comfortably stretching in the light. But what is it that so magically attracts cats? Is it the warmth, or are there other reasons why cats love sunbathing so much? PETBOOK editor and cat behavior expert Saskia Schneider reveals the answer.
A cat luxuriating in the sun—it is a behavior so typical of these animals that even famous comic artist Jim Davis often features it in his Garfield stories. In these tales, the cat frequently chases the sunbeam streaming through the window to take a nap. But why do cats love lying in the sun so much? Most would probably guess it’s mainly for the warmth—and that’s correct. However, there are other intriguing reasons related to our pets’ health. In fact, this behavior is not only instinctive but also biologically sensible.
Sunlight Boosts Mood
Just like in humans, sunlight stimulates the production of serotonin in cats, a neurotransmitter known as the “happiness hormone.” Serotonin affects not only mood but also sleep, appetite, learning ability, and even wound healing. So when cats lie in the sun, it demonstrably improves their well-being—they become more relaxed and content and often seem downright blissful. It’s no wonder many cats follow their favorite sunny spot around.
Warmth Helps with Pain
Sun warmth is much more than just pleasant—it acts like natural heat therapy. Older cats with joint issues or arthritis particularly benefit from the warming effect of the sun’s rays. The warmth relaxes tense muscles, promotes blood circulation, and can even reduce inflammation. That’s why it’s not uncommon for senior cats to doze in the sunlight for hours—it’s a simple form of self-medication. 1
By the way, if your cat shouldn’t lie in the sun for health reasons but suffers from joint issues or arthritis, you can alternatively use a red light lamp. However, you should always supervise, as improper use can also lead to burns.
Cats Use the Sun to Set Their Internal Clock
The internal clock—also known as the circadian rhythm—controls sleep and wake phases, hormone balance, and many metabolic processes. Sunlight is a crucial regulator for this rhythm. For indoor cats that rarely go outside, it’s especially important to regularly experience natural daylight. It signals to the body when it’s day and when it’s night—a factor that significantly contributes to mental and physical health.2
A Sunbath for Healthy Skin and Shiny Fur
Sunlight also has a positive effect on skin and fur. UV radiation has a mild antibacterial effect and can help reduce germs on the skin. Additionally, sunlight stimulates the production of natural oils that keep the fur smooth and shiny. It also promotes blood circulation in the skin—an important contribution to cell regeneration and wound healing. Enjoyed in moderation, a sunbath can be quite nurturing.
Cats Produce Vitamin D in the Sun—But Differently Than We Do
While vitamin D plays an important role in cats for bone structure, muscle function, and the immune system, unlike humans, it is not produced through the skin by sunlight. Instead, cats primarily obtain the vitamin through their diet, especially from meat and organs. High-quality cat foods are enriched with sufficient vitamin D. So, sunbathing has no direct impact on your cat’s vitamin D levels.
Do Cats Need the Sun to Stay Healthy?
Yes and no. The sun is not indispensable for cats—mainly because their vitamin D needs are met through their diet. But they benefit on many levels:
- better mood
- regulated sleep
- pain relief
- skin health
In short, while the sun isn’t a necessity, it’s a welcome bonus for your cat’s health and quality of life. Especially in the cold season or for indoor cats, it’s worth ensuring sunny spots by the window.3
Dangers of Too Much Sun for Cats
As beneficial as the sun is, it also poses risks. Excessive sun exposure can lead to the following problems in cats: 4, 5
- sunburn, especially on hairless areas like ears and nose
- actinic dermatitis—a chronic skin inflammation caused by UV radiation
- skin cancer, especially in light-skinned cats
- overheating, particularly in older or sick animals
Cats with light or thin fur are particularly at risk. Owners should therefore take the following precautions:
- apply UV-protective film to windows
- provide access to shaded areas
- keep cats indoors during the midday sun
- for intense sunbathing: apply pet-friendly sunscreen to ears and nose
- regular skin checks by a veterinarian
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Conclusion
Cats love the sun—and for good reason. Even though they don’t need sunlight to stay healthy, they benefit physically and mentally from sunbathing. It’s important for owners to ensure a healthy balance and protect their pets from the dangers of excessive UV exposure. Then, nothing will stand in the way of the next sunbath in their favorite spot.