Emotional Experiences Can Change the Nature of a Dog's Sleep
The effect of emotional experiences on sleep is different for dogs and people.
Posted Dec 22, 2017
You can't always protect your dog from stressful experiences and their consequences. Just recently we had a visitor come to our house and she was accompanied by her large mixed breed dog, Clyde. It is hard to know what Clyde's genetic background is, however given his size and appearance I suspect he might well be a cross between a Newfoundland and a hippopotamus. Shortly after Clyde arrived, my seven-year-old Cavalier King Charles Spaniel, Ripley, who tips the scale at only around 18 pounds and stands a mere 13 inches high at his shoulder, dashed out of my office to see what was happening. He suddenly found himself face-to-face with the big dog, who gave him a wide-eyed stare which I interpreted as a dominance threat. Apparently so did Ripley, since he immediately jumped onto the sofa and appeared to be trying to hide behind me.
My little old dog clearly seemed to be stressed by the presence of this big visitor. During the short visit Ripley would occasionally look at Clyde and move as though he wanted to get down off the sofa. Clyde would meet him with that wide-eyed stare and Ripley would immediately back off and again try to burrow behind me as I sat on the sofa. After our visitors left, and since it was getting late, I was thinking about preparing for bed. It was then that it occurred to me that since Ripley had been so recently stressed it was highly likely that he was not going to get very much restful sleep this night. Certainly when human beings experience stress during the day it tends to disrupt their pattern of sleep in a predictable manner. The usual symptoms include taking a longer time to fall asleep. In addition the sleep is more restless with more awakenings, and the REM sleep phase (that is the rapid eye movement portion of sleep which is associated with dreaming) a shortened. So I turned to see what was happening with Ripley and found that he was already lying on his sleeping mat in the living room apparently fast asleep as though nothing out of the ordinary had happened.
This observation at first confused me. Research has shown that in many ways the mental processes of dogs are very similar to those of human beings, or at least those of young human children. So usually my own bias is to predict that a dog will react in much the same way that a human will in circumstances involving things like emotional experiences. However, Ripley's behavior reminded me that dogs are not simply four-footed human beings in fur coats. Confronted by something which seemed out of the ordinary, I did what I usually do and went back to do a library search to see if I could dig up some relevant research. The search was successful and I found a study that had been published in The Proceedings of the Royal Society B which seems to address the question.
This recent research on the effect of emotional experiences on the pattern of canine sleep was conducted by a team of researchers at the Institute of Cognitive Neuroscience and Psychology at the Hungarian Academy of Sciences in Budapest, Hungary. The lead author was Anna Kis, and the research was conducted in the laboratory of József Topál.
The study involved 16 dogs, each of which was tested twice, once in a situation where each dog was provided with a brief set of positive experiences and once in a situation which was designed to provide negative experiences. The test sessions were separated by a number of days. The positive experiences involved playing a throw and fetch game or playing tug-of-war (depending upon the dog's preference) accompanied by lots of petting. To provide the negative experiences the owner left the dog alone in the test room and then a stranger entered the room, moved forward in a stalking manner, and then stopped while directly staring at the dog in a somewhat threatening way.
After the exposure to these emotional situations the dogs were taken to a room that they were already familiar with and allowed to sleep for up to three hours. Electrodes attached to the dog allowed the researchers to monitor the nature of the brain activity associated with the dog's sleeping behavior.
As expected the emotional experiences did affect the nature of the sleeping behavior in the dogs. The big surprise was that the nature of these effects seemed, at least at first analysis, to be the opposite of that which we see in people. In humans negative and stressful experiences tend to cause difficulty falling asleep, however the results of this experiment showed that the dogs fell asleep more quickly following a negative emotional episode. It is almost as though the dogs were using sleep as a protective strategy, since sleep allows the dog to psychologically remove himself from the stressful situation. However that's not the whole story.
Experiencing negative emotions also affected the dreaming behavior in dogs in the opposite way that it affects dream behavior in human beings. The stressed dogs spent considerably more time in REM sleep than the dogs who had had the positive experiences. This means that they spent more time dreaming. A number of psychologists who study sleep believe that during the dream state individuals tend to "replay" and try to resolve issues concerning events that have occurred during the day.
There is one way, however, in which the stressful experiences affected the dogs in a manner that is similar to the way they affect humans. Following a series of stressful events the sleep patterns of humans is such that they do not benefit as much as they usually do from the restful effects normally obtained from sleeping. Although the emotionally stressed dogs get approximately 10% more sleep time than the dogs who had positive emotional experiences, the recordings of what was going on in their brain during their sleep shows that they experience less time in the deep sleep stages. It is deep sleep which has been shown to have the most restorative effects both psychologically and physically. This suggests that, just as humans frequently have a less than refreshing night's sleep after a difficult day, dogs may be troubled by a similar problem.
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Kis A, Gergely A, Galambos Á, Abdai J, Gombos F, Bódizs R, Topál J. (2017). Sleep macrostructure is modulated by positive and negative social experience in adult pet dogs. Proceedings of the Royal Society B, 284: 20171883. http://dx.doi.org/10.1098/rspb.2017.1883