Do wolves sleep and dream like dogs do?

The growing interest in canine sleep research is due to its advantages in studying the sleep of a domesticated species adapted to the human environment. Evolutionary adaptations to environmental circumstances (such as sleeping in a protected environment) could have shaped sleep as humans progressed and gained control over their environment. Thus, similar changes in sleep would be expected in other species adapted to the human environment. For example, dogs, like humans, sleep more shallowly when in unfamiliar surroundings.

To better understand the effects that domestication and cohabitation with humans have on sleep phenotypes and physiology, comparing the dog with its wild counterpart, the wolf, offers a perfect opportunity.

Although comparative studies between the dog and the wolf have already been carried out, the neural processes of the wolf remain a largely unexplored field, as Anna Bálint of Eötvös Loránd University in Budapest, Hungary points out.

She, Vivien Reicher of the aforementioned university, and their colleagues used electroencephalography to measure the brain activity of seven wolves while they slept. These wolves had been raised by humans and were widely socialized. The technique for measuring the brain activity of sleeping wolves is the same as that used to measure that of sleeping domestic dogs.

A wolf sleeping while its brain activity is measured with electrodes. (Photo: Department of Ethology / Eötvös Loránd University)

The research team managed to measure in wolves the main phases of the sleeping process that humans experience and that have also been detected in dogs: light sleep, deep sleep and rapid eye movement (REM) phase. This last phase has traditionally been the one that has aroused the most scientific interest, since it is the phase in which humans and other higher animals dream.

It may seem surprising that wolves can be measured by electroencephalography in the same way as domestic dogs. However, by raising a wolf in the company of humans and socializing it intensively from a very young age, they can be handled and comforted much like dogs. During the experiments, the wolves were surrounded by familiar people, who petted them until they calmed down, drowsed and eventually fell asleep. When the wolves became nervous, the handler and experimenter calmed them down with hugs and petting until they fell asleep again.

Although young dogs and wolves showed a fairly similar distribution of sleep phases, the time spent in REM sleep appeared to be less in dogs than in wolves, and this difference is even more apparent in older animals. This finding is especially intriguing.

The study is titled “Non-invasive sleep EEG measurement in hand raised wolves.” And it has been published in the academic journal Scientific Reports. (Font: NCYT by Amazings)