Most people know by experience that stressful days can lead to sleepless nights, but little work has been done, the researchers note, to find out if the same is true for other animals. In this new effort, they sought to learn more by recording brain waves of sleeping dogs.

To find out if sleep patterns in dogs change due to stressful situations prior to sleeping, the researchers enlisted the assistance of 16 pet dogs of different breeds and their owners. Each of the dogs was subjected to either a positive or negative experience. A positive experience was something the dog was known to like, such as being petted or engaging in playing catch. Negative experiences included being tied to a door for a length of time while being ignored by the owner or having a researcher stare threateningly directly into its eyes.

All of the dogs were fitted with EEG sensors, and after their positive or negative experiences, were allowed to go to a designated place to sleep.

The researchers report that the dogs that had experienced a stressful event went to sleep approximately twice as fast as the relaxed dogs, a behavior that has been seen before. Prior research suggests dogs attempt to separate themselves as quickly as possible from their stressful feelings. All of the dogs were allowed to sleep up to three hours as researchers monitored their brain waves. The researchers found that those dogs that had undergone negative experiences spent on average 20 fewer minutes of deep sleep than the dogs that had positive experiences. They did not spend it awake, however, instead, they simply had more minutes of REM sleep.

Journal reference: Anna Kis et al. Sleep macrostructure is modulated by positive and negative social experience in adult pet dogs, Proceedings of the Royal Society B: Biological Sciences (2017). DOI: 10.1098/rspb.2017.1883

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