Our sun is the most important influence upon life on this planet earth. Every living thing that is outside during daylight hours has evolved over millions and millions of years in a close partnership with the sun.
The patterns of natural sunlight exposure that our dogs (and we) are impacted by control the deepest and most important biorhythms of our bodies. 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 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).
There are two sorts of UV light of slightly different wavelengths – UVA and UVB. UVA is absent at sunrise, then relatively stronger in mid-morning and late afternoon sunlight; UVB is relatively stronger in the middle of the day.
When Your Dog Needs Sunlight
Ideally your dog should be exposed to raw sunlight for a time in early morning (sunrise) light, then 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 to be exposed 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. Most importantly, sunlight striking the back of the eye (the retina) and skin first thing in the morning has a massive impact on controlling your dog’s circadian rhythm. Special 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 make your dog sleepy, ready for bed.
Sunlight Affects Circadian Rhythm
A healthy circadian rhythm is critically important for good health and controls patterns of brainwave activity, hormone production, cell regeneration and many other biological/biochemical activities over the day/night cycle. 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 decrease 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. Then 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 our physiology and biochemistry, something that is very poorly understood in medicine in general.
Daily Light Cycle
It’s important to understand that our dogs need to be exposed to the whole daily cycle of changing proportions of different wavelengths (or colors) of light that the sun naturally provides, if you want them to be healthy. Dogs have evolved over millions and millions of years being exposed to the sun all day, every day. It’s only very recently in human history that artificial lighting has been common-place.
Artificial light has a much different spectrum than natural (raw) sunlight, and has multiple adverse impacts on health. Artificial lighting has a high proportion of blue light and 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 supress melatonin by 80 percent. Incandescent bulbs supress melatonin by 40 percent. A candle only supresses melatonin by two percent.
Not only does your dog need to get exposure to raw sunlight as much as is humanly possible, you need to minimize or stop any 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 night time part of their circadian cycle. Melatonin is critical for this because with the red light, melatonin is increased.
Avoid Blue Light
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 such as 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 dogs, right?)
Here are some important action steps to help your dogs get healthy light in their lives:
- Avoid any use of screens and devices (preferably after sunset and especially for at least two or three hours before bed). This includes watching TV 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 night time lighting (as a second best choice).
- Make sure your dog has good exposure to raw sunlight, preferably in all of the important periods of the day: sunrise and early morning, midday, late afternoon and sunset. I’d suggest up to 30 to 60 minutes morning and late afternoon to 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. Don’t overdo it!