UV Bulbs vs. Sunlight: Which Light Is Right for Your Turtle?

“I’m worried about my turtle. He does not seem to be as active as he was when I brought him home. I have UV lighting in the tank, but is it enough, or should I keep him in direct sunlight for some time?”—Schweta

Why Natural Sunlight Matters for Your Turtle's Well-being

Using the right UV bulb is a solid choice, but sunlight can offer something extra that artificial lights might lack. As we learn more, we discover what we might be overlooking.

For instance, years ago, few people thought about how tank lighting affected a turtle's health. We now know that a turtle's retina reacts to UV light (1), but we still don't know what other parts of light might be important.

What Makes Natural Light Special for Turtles?

Studies show that people who don't get enough natural light can suffer from depression and sleep issues. (2) Office artificial lights don't affect the human body the same way. Perhaps later we'll find that some turtles have health problems and don't breed well in captivity because they're missing something in their diet or lighting.

We've learned that sick sea turtles need natural sunlight because it's a strong source of vitamin D. (3) Just as the importance of antioxidants was discovered long after vitamins, there's still much to learn about the best lighting.

How to Safely Give Your Pet Turtle Sunlight

When you take your turtle outside for natural light, don't just put its tank in the sun. A larger separate enclosure is better because putting the tank in the yard can cause several issues, such as:

Overheating
This worries me most because a small tank can heat up quickly. In the wild, a water turtle has a basking spot but will jump back into the water to cool off when it gets too hot. Your turtle MUST have a shaded area to escape to, and don't worry if it seems to hide every time you check instead of basking.
Dehydration
Water must always be available. Keep it in the shaded part of the outdoor enclosure so it stays cool.
Getting Too Cold
If it's cool but sunny, you can put your turtles out because they can bask and warm up. If it's very cold and overcast, don't put them out—keep them inside with the correct artificial lighting.
No Hiding Shelter
Turtles need 2 to 12 hours of light daily, but once they've gotten enough UV rays, they need to get away from excess. A hide area lets them escape the light and any curious dogs or cats that might come into the yard.

What If You Can’t Take Your Turtle Outdoors?

Not everyone has an outdoor space for their pet turtle to get sun. If you don't have a yard and live in an apartment without a balcony, and your turtle must stay inside, at least follow the advice in this video:

Where to Buy a UV Light Source

You can purchase the correct UV lighting on Amazon or at your local pet shop.

References

(1) Ventura DF, de Souza JM, Devoe RD, Zana Y. UV responses in the retina of the turtle. Vis Neurosci. 1999 Mar-Apr;16(2):191-204. i.nlm.nih.gov/10367955/

(2) Harb F, Hidalgo MP, Martau B. Lack of exposure to natural light in the workspace is associated with physiological, sleep and depressive symptoms. Chronobiol Int. 2015 Apr;32(3):368-75. i.nlm.nih.gov/25424517/

(3) Garefino VE, Milton SL. Influence of Sunlight on Vitamin D and Health Status in Green (Chelonia mydas) Sea Turtles with Fibropapillomatosis. Animals (Basel). 2022 Feb 16;12(4):488. i.nlm.nih.gov/35203196/

This article is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from your veterinarian. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.