Today my three dogs are lying around like lumps. They show little motivation to do anything, and Dancer, the oldest of the group (and the most predictable) even shows little enthusiasm when it comes to barking at the postman. My usually alert dog arrives at the door well after the mail has already been dropped into the box and the postman has already descended the stairs and is halfway back to the street. Even my grabbing the leashes and preparing for a walk doesn't seem to bring a lot of joy to my pets. Furthermore, other than sleeping for many more hours than is customary each day, the only thing that my dogs seem willing to do is to bump my leg with their noses and whimper—a sure sign that they are begging for a treat.
As a psychologist, any changes in the usual behaviors of the people or pets that I live with attracts my attention. Thus it happened that while I was musing about the situation the answer appeared on the television. It actually came from the mouth of the local weatherman. He was complaining that in the last five weeks in the area where I live there had only been 28 hours of sunshine. Now if I were considering human behavior under similar environmental conditions I would probably be seriously considering the possibility of "Seasonal Affective Disorder" or SAD. You probably know of this as the "Winter Blues". It is a form of depression which millions of humans suffer from, especially in the winter months when there is little sunshine and the overall daytime light levels are low. In humans the symptoms include lethargy, depression, social withdrawal, fatigue and craving for comfort foods – exactly the same symptoms that I was seeing in my dogs.
The fact that these symptoms are related to light levels is well-established. For example, in Florida the incidence of SAD in the wintertime is only about 2%, as opposed to an incidence of 10% in New Hampshire where the winter light levels are considerably lower. Thus it is not surprising that one standard treatment for SAD symptoms is increased exposure to full spectrum light that mimics the light composition of normal daylight.
Do dogs suffer from SAD? Some data comes from a survey conducted by a leading veterinary charity in the UK. PDSA (The People's Dispensary for Sick Animals) found that approximately 40% of dog owners saw a considerable downturn in their pet's moods during the winter months. In addition half of the dog owners felt that their dogs slept longer, with around two in five reporting their pets to be less active overall. According to the survey, the symptoms are not specific to dogs, since one in three cat owners also claim that their pet seemed "sadder" and less playful during the wintertime. For both dog and cat owners one in four of those surveyed reported that their pet's appetites increased in the winter.
The key to all of these changes appears to be the effect that light has on two different hormones. The first is melatonin, which is a hormone produced in the pineal gland. It plays a role in regulating sleep cycles. The pineal gland is light sensitive and melatonin is usually secreted at night in darkness—the production of melatonin is actually inhibited when light hits the retina. So in response to low light conditions found in the winter more melatonin would be produced. Melatonin has a number of effects and the major ones include causing a person to relax and get sleepy and lethargic. For a number of people, when melatonin levels are high enough, they may develop feelings of depression and despair along with reduced motivation to engage in work and play activities.
The second culprit is another hormone called serotonin. In the brain, serotonin affects appetite, mood, and sleep. Low levels of serotonin are also known to have a distinct effect on the mood of people and animals. Most of the anti-depressive medications, such as Prozac, depend upon boosting the level of serotonin in the brain. Sunlight is necessary for the production of serotonin. This hormone is sometimes referred to as the "feel good" substance in the brain, which is one reason why resorts in sunny latitudes are so popular and pleasurable and are "happier places". Serotonin release is also associated with many unhealthy comfort foods such as cakes, sweets, and chocolate. This is one reason why humans turn to food as a home remedy to battle the winter blues and probably why my dogs are busy begging for extra treats this winter.
Is there some way to combat this seasonal onset of depression in our pets? Given that the absence of bright light seems to be the major cause, most of the solutions involve boosting light exposure. Placing your pet's bed under a skylight or close to a window or glass door can help take advantage of what little light there is. You may have to change the schedule of your dog walks to make sure that you are outside during the brighter portion of the day to maximize exposure to daylight. Turning up interior lighting helps, but the composition of the light is important. The closer it is to natural daylight the more therapeutic is its effect. For humans battling SAD there are light boxes with special bulbs, and people are encouraged to use these for about three quarters of an hour each day. I am told that there are even some light boxes specifically designed to be used for dogs. However with the rise of compact fluorescent bulbs (the high efficiency replacements for tungsten light bulbs) white light sources that mimic daylight can be purchased rather inexpensively. Just make sure that you get light bulbs which are labeled as being "full spectrum" or "daylight" bulbs, although some experts say that "cool white" will also work (although perhaps not as well). Turn these lights on for at least an hour or so each day, and fuss or play with your dogs a bit so that their eyes are actually open and their retinas are exposed to the incoming light. If you do this then perhaps you can save your dogs from a bout of the winter blues. Since you are also being exposed to that same additional light it may also boost your own mood in the dark days of the winter.
Stanley Coren is the author of many books including: Born to Bark; Do Dogs Dream? The Modern Dog; Why Do Dogs Have Wet Noses? The Pawprints of History; How Dogs Think; How To Speak Dog; Why We Love the Dogs We Do; What Do Dogs Know? The Intelligence of Dogs; Why Does My Dog Act That Way? Understanding Dogs for Dummies; Sleep Thieves; The Left-hander Syndrome
Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission