Colored Lights & Reptiles | Myths the pet store told me 12

Colored lights don’t belong within herpetoculture. The band Guess Who wrote the lyric ‘colored lights can hypnotize’ for their song American Woman. When writing those lyrics, I’m sure they never intended them to refer to the world of herpetoculture. They may have been referring to some type of mind altering substance but they weren’t referring to reptiles and color vision. Moving onto the subject at hand, there’s an inordinate amount of reptile owners who for whatever reason believe colored lights are good for reptile night heating. This belief, is no doubt, due in part to the advertising on the boxes of these colored bulbs.

I too am guilty of recommending these colored bulbs when I worked the retail sector of the reptile world. Not making excuses for myself; at the time we had no other information to go on. The reptile industry of herpetoculture & the science of herpetology don’t always communicate which leads to many numerous misnomers and misinformation being given out to the public at large. The debate of who’s at fault is for another piece which would talk about the Ivory Tower and those too lazy to climb it.

Geckos and Coloured Lights

In 2004 it was shown that nocturnal geckos were not only capable of acute vision in dim light but they use the cones of their eyes for color vision in dim light. The same paper stated that while geckos had lost the red sensitive cone and oil droplets which would allow them to discern the color red, they still perceived not only ultraviolet light which is beyond human perception, they also see blue and green light. The two authors also suggested that the gecko eye lenses are probably multifocal which enhances the spatial resolution of their color vision creating well focused images on the retina.

Red Heat Bulb

Red Light

I’m sure with the above points we can agree any light, colored or not, will in fact disturb the normal circadian rhythm also called the sleep wake cycle. This is particularly true if we take into account the geckos, nocturnal as they might be are also seeing into the ultraviolet spectrum. Therefore any light placed around or on the enclosure would be indeed visible. Within this same paper it’s said “most diurnal vertebrates have cone-dominated retina with few rods and lizards have gone to the extreme: their retina only cones (Walls 1942) and provide them with excellent colour vision (Wagner 1932).”

Further studies done in lizard vision bear out results that many if not all lizards possess color vision of some type whether it be tetrachromatic or dichromatic. The fact remains that they are perceiving light and many of them seeing into the ultraviolet spectrum. Again from this we can infer that any light can and is seen by lizards.

Before moving on to the snakes here’s something else to consider. Every field herper I know of sees a decrease in reptile activity during the full moon. Many of us reason this is due to predation exposure. Thus meaning on nights of the full moon that predation risk is far higher than those without a full moon. To my knowledge the luminosity (actually a reflection of sunlight as the moon doesn’t have its own light source) of the moon and its potential effects on reptile predation have yet to be examined and this may be an interesting paper for future research.

Snakes and Coloured Lights

Ophidians or snakes are said to have evolved from lizards some millions of years ago. So its understood that just as we as human primates inherit certain characteristics from our families so do all animals inherit things from the ones that came before them. In two different studies it’s found that one of the least evolved snakes Python regius has ultraviolet sensitive sight in which one paper posits, this may be used to track the visually ultraviolet reflective urine of their chosen rodent prey. Even further it’s said Python regius is dichromatic and may also have the potential for being trichromatic meaning it sees three colors instead of being effectively color blind as most people presume. If the lowest evolved snake has such sensitive vision and with it being known that the most highly evolved snakes Viperidae do have some color vision as well as the ultraviolet light sensitivity seen in lower snakes;

I would infer that all squamates have not only dichromatic vision but that potentially all of them have an acuity to sense ultraviolet light.

Reptile Vision

Understanding that, let’s now look at something obvious. The visual spectrum humans can see is between 400nm-700nm. Ultraviolet light which humans cannot see is between 320nm-100nm. We now understand that reptiles see better than previously perceived (pun intended) so let me ask you this? Can you see the light emitted by that colored bulb? What makes you think the reptile which has more acute vision than you cannot?

To the reptile that can see into the ultraviolet spectrum I infer it would be very bright. Therefore, when were attempting to heat our reptiles at night while not disturbing them by using colored bulbs it turns out we are indeed disturbing the circadian rhythm. It’s been shown every living thing has a circadian rhythm which they experience, if you disrupt that rhythm then behavioral changes can and often do occur to compensate for the alterations.

CHEI’ve personally witnessed alterations in behavior within a week or so of changing the red incandescent bulbs on my bearded dragon Pogona vitticeps for a non-light emitting ceramic heater of appropriate size. He became more active during the day and began feeding better than when the red incandescent was used. No formal studies have been conducted on the circadian rhythms of squamates to my knowledge but I do think were capable of inferring some basic tenets of sleep deprivation or the interruption of normal circadian cycles. As far as a nocturnal species are concerned as I stated above I would say there would be a higher stress load on such a reptile when being exposed to what must be an excessively bright light due to the natural make up of their vision.

In closing please do yourself and your reptile pet a favor and buy only ceramic heating elements that are not light emitting to keep them warm at night and if necessary by an under tank heater to supplement the ceramic heating element. If you want to watch your pet’s behavior at night buy some night vision goggles. Here is a link to a cheaper pair which is an affiliate link if you’re serious about stalking nocturnal reptiles.


Nocturnal colour vision in geckos Lina S. V. Roth and Almut Kelber The Royal Society Biology Letters

The Photoreceptors and visual pigments in the retina of boid snake, the ball python (Python regius) A.J. Sillman, J.K. Carver and E.R. Loew

12 thoughts on “Colored Lights & Reptiles | Myths the pet store told me

  • johnftaylor Post author

    Muril, first of all thanks for the comment! We would love to hear the results of your changes! I am willing to bet you will see a marked change in behavior after the CHEs are installed and running for about a week.

  • Muril Stone

    after reading this i was prompted to remove the lights from my enclosure. i moved two of my blood pythons into a separated enclosure and had lights in there for heat. overnight i found that both of them had become jumpy (stressed) and had marked it up to the move. well they are both eating but are not calm like they have always been. so i have ordered two CHEs to replace the lights for night heat. i will be interested if there is a behavior change…thanx for the info!

  • johnftaylor Post author

    Sharon, thanks so much for your comment. We will be publishing a full report for on the lighting of reptile which will only be available for our newsletter subscribers and they will also be getting some other extras that will not be available to the general public. We look forward to sharing more care and natural history information with our readers through the upcoming year!

  • Sharon Weber

    I am so glad that I was given a link to your site! I will sign up for the newsletter as well. I am delighted to see your research. I have noted that many are not given the credit they deserve – whether reptiles and other animals for their cabilities, or ancient humans or other cultures for theirs. And, um, the red lights go out tomorow…and I will have to check out those night vision goggles I suppose.

  • johnftaylor Post author

    Thanks Robert, we really appreciate the input and be sure to look out for the full report on lighting coming soon exclusively to our newsletter subscribers. It’s going to very in depth on the various lights and why they don’t work as well as an in depth look at reptile vision etc. You can sign up for the newsletter here if you haven’t already.

  • Tortoise Blog

    Thanks John, I’ve read the forum posts. The tortoises’ lights are not on during the night so it does not disturb him. I shall keep an eye out for other info on the subject.

  • Robert Kilpatrick

    This makes perfect sense, Of my two iguanas (housed separately). I changed one enclosure to a ceramic heat emitter and that iguana is showing a better response with my T Touch therapy. The other iguana that is under the red heat bulb at night is sleeping more than the other during daylight hours and is very skittish when first approached. I will change that bulb to a heat emitter asap!

    Very good read,well worth the wait.

  • johnftaylor Post author

    Elizabeth, thanks for your comment I must say it is nice to hear from our readers whether they are confirming our findings or give us further food for thought. We of course welcome any additional readers that you care to send our way.

  • johnftaylor Post author

    Well, I have read studies specifically stating that red lights are visible to Tortoises. Now whether using them during the day is detrimental per se I couldn’t say with confidence. However, there is a discussion addressing this here which outlines this as well with varying opinions. Personally, I believe the scientific evidence that shows that yes they can see the red lights and that leaving these on at night when they would normally experience darkness it does disturb them. Thanks for your comment and we look forward to bringing you further information on this and many other subjects regarding reptile husbandry.

  • Elizabeth Semple

    From my experience breeding and keeping Bearded Dragons, Leopard Geckos and various Rhac species your article neatly sums up my findings regarding the husbandry of these diurnal and nocturnal herps. For many years I have advised my customers and other information seekers against the use of any coloured bulbs for night time use. Many times customers have contacted me for assistance with their failing bearded dragon. They usually ask me:”Why is my beardie lethargic and not eating?” One of the first things I review with them is husbandry, and 9 times out of 10 incorrect lighting is used. Unfortunately most folks are sold expensive and detrimental red heat bulbs to use as a night heat source. Once these lights are removed, and I assure folks that their dragon is perfectly fine without any light/heat at night, the dragon perks up, sometimes as rapidly as after one night without the “red light”. Normal eating and sleeping patterns are returned and the dragon begins to grow and thrive again. I now have a secondary source to refer my customers to to reinforce my recommendations. Thanks John – great article.

    Elizabeth S.
    DarkSide Dragons

  • Tortoise Blog

    Informative article. Are there any views on using red bulbs during the day? I would like to switch to a ceramic heater for our tortoise instead of the red bulb but my wife is not convinced. The red bulb annoys me, I’m sure it annoys the tortoise also :)
    Thoughts welcome.

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