Que-Eras-Serotonin – It Leaves Our Pets in Winter – But Light Therapy Can bring it Back

by Nancy Blue

Need proof that light therapy from full spectrum light boxes for pets increases serotonin—the feel good chemical that helps combat seasonal affective disorder (SAD)?  How about this:  

On Facebook, there was a photo—on a non-commercial we-love-dogs page—of four dogs lined up in a row, all basking in a ray of sunlight coming through the doorway.  Seven hundred people in one day commented how their pets love to soak up the sun.  Here is the gist of a few of their comments:


"Solar recharging...my dogs and cats do this daily."

"My dogs will argue over the sunny spot as it gets smaller in the room."

"Fletch will climb the stairs to follow a ray of sun."

"My cat moves from one spot to another to follow the best sunrays."

"My cat, at death’s door suffering from kidney failure and old age, dragged her skeletal frame across the lawn with her last smidgen of energy to a sunny spot, just to bask in those lovely rays one last time."


Who ya gonna believe, a vet or your very own best friend?  True, vets have differing opinions about whether dogs and cats suffer from seasonal affective disorder, but it’s clear that our four legged friends know the benefits of the bask!

We know that cats and dogs love sunlight, and research indicates that many of them show signs of seasonal depression.  

Dr. Elizabeth Colleran, DVM, a feline veterinarian in Chico, California—where sunny summers distinctly contrast with cold rainy winters—indicates, "I really do see a difference, I'm absolutely convinced of it...”  

According to Dr. Colleran, it is logical to assume domestic cats, just like cats in the wild, are impacted by the change of seasons in a variety of ways:  For instance, exposure to sunlight is known to regulate their mating behaviors.

Dr. Debra Givin, DVM in Portland, Main is not convinced that pets get SAD, but she says, "Certainly in the Northern latitudes, I've on occasion thought for the older cats, as they face another winter, some of them seem to take a turn for the worse. In the wintertime, life is harder. It's cold and dark."

Another expert, psychology professor and animal behaviorist Mary Lee Nitschke, at Linfield College in Portland, Oregon says, “Light... can stimulate the body to release hormones that have an uplifting effect on mood.”  She recommends that pets showing signs of depression get at least 30 minutes a day to bask in full sunlight.


Veterinarian Elaine Pendlebury of PDSA—England’s leading charitable organization for the welfare of pets—indicates that more darkness could impact our pets’ moods. And PDSA surveys found that half of dog owners in England—an area known for sunshine deficit—noticed their dogs sleeping more in the winter months, and one in three cat owners indicated their cats had a decrease in playfulness in the darker season.

To help you decide what to do about depression and related symptoms in your pets, in winter or any time, let’s get familiar with some terms.

Full spectrum lighting:   

Adequate exposure to full-spectrum light has many health benefits. Full spectrum lighting delivered via light therapy mimics natural sunlight.  Just turning on lights all day or using reptile lights such as those sold in pet shops does not fill the bill.  A 10,000 lux light box delivers full spectrum light in a safe, easy to use source.  As described in the Journal of Biological Rhythms, 10,000 lux is:  equivalent to ambient light intensity just after sunrise or just before sunset.

Que-Sera-Sera-tonin:  Is that endorsed by Doris Day?  Maybe...but we are talking about serotonin, known as the feel-good-chemical, that when lacking is closely associated with depression.  

In winter when sunlight decreases, serotonin levels drop.  Light therapy, known to increase serotonin levels in humans and animals, can fight the dark day doldrums by assuring you get needed light year-round.  Even veterinarians that are inclined to invalidate SAD in our pets, know that our fury friends suffer depression, routinely treated with drugs like Prozac.  Vets also concur they see more depression in winter, but some chalk it up to our pets mimicking our own SAD.  No matter if they are mimicking our  winter blah behavior, or reacting directly to  decreased hours of sunlight, the result is the same—less perky pets, tending to eat and sleep more, and in some cases, full blown pet depression.

The only question is, what will you do to help your pet cheer up when they become less playful and/or depressed.  Since Prozac and similar drugs have side effects, the drug free alternative is light therapy.  And you’ll up your own cheerfulness quotient by plugging in a light box where you hang out with the kids (i.e. pet kids).  Yes!  It works great on humans too!

Mel-o-toning:  Is that music therapy for mammals?  No, it’s melatonin, a hormone that the brain produces more of when it’s dark, which causes drowsiness.  

In cloudy weather, people and pets tend to want to sleep more.  Light therapy helps keep melatonin levels appropriate:  When light hits the eye, melatonin is inhibited.  Use of full spectrum light therapy assures our pets don’t have too much of this so-called “hormone of darkness”.

Circadian Rhythms:  Doggie dance therapy?  No, it refers to the sleeping and waking cycles of all living things.  

Darker days can throw these rhythms out of balance, causing tiredness and lethargy.  Studies indicate that sleep deprivation has an antidepressant effect, but we don’t advise submitting your best friend or yourself to up-all-night torture (which you could do by blasting the Macarena on the stereo from 10 p.m. to 5 a.m.).  Simply provide 40 minutes or more of full-spectrum light from a quality 10,000 lux light box.  Your dog or cat will benefit from balanced circadian rhythms—enjoying the optimal amount and quality of sleep, and waking up refreshed and ready for the usual doggie doings and kitty capers.

Cort-a-soul:  Dating for spiritual types?  Actually, that is cortisol, a substance associated with stress.    

Too much of it brings undue stress levels.  Studies of 10,000 lux light exposure indicate that cortisol decreases with full spectrum light.  So, in addition to fighting depression, use of a quality light box can help living creatures to relax.  

In conclusion, full spectrum light therapy for cats and dogs will increase serotonin and help to regulate melatonin, circadian rhythms, and cortisol, leading to a brighter, more relaxed mood.  You will notice with recommended use of a 10,000 lux light box your pets begin to display their usual healthy sleeping patterns and perky personalities.  Exposure to full spectrum light also helps regulate appetite, body aches and pains, and aggression, all things associated with decreased serotonin, and depression or SAD.   Now you have the facts, and can make the right choice for your pets suffering seasonal or other depression, or general blahs caused by living year-round in a climate with a shortage of sunny days.