The sun is the most important influence upon life on planet earth.
Every living thing that is outside during the day has evolved over millions and millions of years in close partnership with the sun. So, do dogs need sunlight too, even though they’ve adapted to living indoors?
Is Sunlight Good For Dogs?
Yes, sunlight is not only good for dogs … dogs need sunlight. it’s essential that dogs get sunlight at different times of day. Sunlight is vital to your dog’s wellbeing in many ways.
The patterns of natural sunlight exposure control the most important biorhythms of your dog’s body. In fact, all mammals that are active during the day are very sensitive to the sun and need exposure to raw sunlight throughout the day to be healthy.
Why Your Dog Needs Raw Sunlight
Raw sunlight has a natural spectrum of light from infrared (IR) right through to ultra-violet (UV). If you filter sunlight through glass, the UV light is absorbed and no longer reaches your dog’s skin and eyes (both of which are highly photosensitive).
When Do Dogs Need Sunlight?
There are two types of UV light with slightly different wavelengths – UVA and UVB. UVA is absent at sunrise, then relatively stronger during mid-morning and late afternoon. UVB is relatively stronger in the middle of the day.
Your dog should be exposed to raw sunlight in the early morning (sunrise). Then again in the middle of the day and in the late afternoon or at sunset.
Dogs (and all mammals) have evolved living outside, exposed to the sun all day. Not only do they need sunlight, they need exposure to the changing nature of raw sunlight throughout the whole day to be healthy.
- Sunlight landing on your dog’s skin and in her eyes triggers all sorts of important metabolic pathways.
- Sunlight hitting the back of the eye (the retina) and skin in the morning has a big impact on your dog’s circadian rhythm.
- Light-sensitive cells in the eye act through the hypothalamus (in the brain) to regulate the circadian rhythm through complex hormonal pathways.
Melatonin is the most important hormone for regulating a healthy circadian rhythm. Melatonin levels increase in the late afternoon and evening from the influence of red light and darkness, and calm your dog. They make her sleepy, ready for bed.
Sunlight Affects Your Dog’s Circadian Rhythm
A healthy circadian rhythm is critical for good health. It controls patterns of brainwave activity, hormone production, cell regeneration and many other biological/biochemical activities over the day/night cycle. Research shows that circadian rhythms even affect gut microbiota … impacting your dog’s immune and metabolic function (1).
Disruption of the circadian rhythm over time can lead to many chronic diseases. This rhythm is very sensitive and is easily disrupted by artificial light, as I will explain later (this is VERY important).
Early morning light has no UV light – it has blue, green and red light. This pattern of light kick-starts your dog’s metabolism, wakes everything up and gets it moving for the day. The higher levels of blue light act to reduce melatonin levels.
In the middle of the day, as the sun shines through less of the atmosphere, we are exposed to the full spectrum. From IR right through to UV, with the highest levels of UVB.
In the evening the spectrum of light from the sun shifts to red and IR, without any blue light present at all.
All mammals are highly photosensitive, not only to the presence or lack of light, but to the color or spectrum of any light that reaches their skin or eyes. Light has quantum effects on the deepest levels of your dog’s physiology and biochemistry. This is something that is very poorly understood in medicine in general.
Why Do Dogs Sunbathe?
Most dogs enjoy being outdoors during the day … and dogs will often sunbathe. Even Northern breeds who prefer the cold will often find a spot of sun to lie in.
And It’s important to remember that your dog needs to be exposed to the entire cycle that the sun provides, if you want her to be healthy. Dogs have evolved being exposed to the sun all day, every day. It’s only recently that artificial lighting has been commonplace.
Why Artificial Light Is Harmful
Artificial light has a much different spectrum than natural (raw) sunlight … and it has many adverse impacts on health. Artificial lighting has a high proportion of blue light. It stays the same all the time, unlike the natural changes in the spectrum of light from our sun over a whole day.
The artificial lighting that has the bluest light (and a complete lack of IR and UV) is LED. Fluorescent lighting is equally bad. Both LED and fluorescent lighting suppress melatonin by 80 percent.
Incandescent bulbs suppress melatonin by 40 percent.
A candle only suppresses melatonin by two percent.
So, not only does your dog need to get exposure to raw sunlight as much as possible, you need to reduce or stop her exposure to artificial light.
This is especially important in the late afternoon or evening around sunset, when the body is waiting for signals from the higher levels of red and IR light to trigger the nighttime part of the circadian cycle. With the red light, melatonin is increased.
Avoid Blue Light For Your Dog
But guess what? Blue light destroys melatonin! This is how blue light totally upsets a healthy circadian rhythm.
Other strong sources of blue light are flat screen televisions and LED powered screens on devices like smartphones, tablets and computers. Avoid them or wear blue blocker glasses if you can’t (because you have to be healthy to look after your dog, right?)
How To Increase Sunlight For Your Dog
Here are some important action steps to help your dog get healthy light in her life …
- Make sure your dog has good exposure to raw sunlight, preferably in the important periods of the day … at sunrise, early morning, midday, late afternoon, and sunset. I’d suggest up to 30 to 60 minutes in the morning, late afternoon and evening, and maybe 15 to 30 minutes in the middle of the day. Do less if the sun is very intense. You’ll have to calibrate this to your environment, of course, and don’t overdo it!
- Avoid any use of screens and devices (preferably after sunset and especially for at least 2 to 3 hours before bed). This means not watching TV or using devices with your dogs in the room!
- Use dim red lights after sunset. Red light has the least damaging impact on melatonin. Swap out your lighting to incandescent bulbs with a yellow, orange or red filter for nighttime lighting. This isn’t the ideal option but it’s the second-best choice.
By making sure your dog gets the right amount of sunlight at different times throughout the day, you can help her live a healthier life.
- Voigt RM, Forsyth CB, Green SJ, Engen PA, Keshavarzian A. Circadian Rhythm and the Gut Microbiome. Int Rev Neurobiol. 2016;131:193-205.
- Cho Y, Ryu SH, Lee BR, Kim KH, Lee E, Choi J. Effects of artificial light at night on human health: A literature review of observational and experimental studies applied to exposure assessment. Chronobiol Int. 2015;32(9):1294-310.
- Russart KLG, Nelson RJ. Artificial light at night alters behavior in laboratory and wild animals. J Exp Zool A Ecol Integr Physiol. 2018 Oct;329(8-9):401-408.
- Bonmati-Carrion MA, et al. Protecting the melatonin rhythm through circadian healthy light exposure. Int J Mol Sci. 2014 Dec 17;15(12):23448-500.
- Willems JS, Phillips JN, Francis CD. Artificial light at night and anthropogenic noise alter the foraging activity and structure of vertebrate communities. Sci Total Environ. 2022 Jan 20;805:150223.