For the first time, scientists have been able to track wolves' brain activity during sleep and compare it to how dogs sleep.
One of the mysteries of sleep physiology is the change that occurs during the transition from wild life to "civilization." Such transformation is accomplished not only by humans but also by domesticated animals. So scientists are trying to compare their sleep to that of their wild relatives. Ethologists at the University of Budapest (Hungary) have managed to conduct such a study on wolves for the first time. They wrote this in an article published in the journal "Scientific Reports ".
At night, people settle down in a warm, dry and safe home so that after a good night's sleep, they can start their day's activities. This condition is rare in the wild, and our ancestors slept in other, more disturbing, environments. This has to affect the pattern and nature of sleep itself. It's possible that modern humans sleep differently than they did in the distant past. To find out whether this is true, and how sleep has changed as the economy has developed, scientists turned to domesticated animals whose living conditions have undergone similar changes.
The idea is to compare sleep physiology between them and their wild relatives and find the differences. From this point of view, dogs and wolves seem to be the most suitable candidates - they are still very close, but have led completely different lifestyles for a long time. However, wolves are still wild, and so far no one has been able to attach electrodes to them to perform electroencephalography (EEG) while placing them in an environment where the animals can sleep peacefully.
Recently, Hungarian ethologists led by Vivien Reicher succeeded in doing such work for the first time. The scientists took advantage of the fact that wolves raised among humans, while not as fond of them as dogs, are accustomed to and feel comfortable with human presence and attention. Therefore, experiments were conducted on seven wolves in captivity. EEG electrodes were attached to the animal's scalp to track all stages of sleep. The wolves sleep in the presence of their keepers, who comfort the animals when they wake up. Similar data were collected on dogs of the same age as wolves.
Recordings of brainwave activity indicate that wolves have sleep stages similar to those of dogs. The main difference is the duration of the REM phase, which is longer in wolves, and this difference increases with age. Recall that during nighttime rest, the mammalian brain exhibits different types of activity that replace each other in a certain sequence, passing through corresponding stages. The most notable of these are slow-wave and fast-paced (REM-) sleep. During fasting, electrical activity in the brain fluctuates frequently, almost like when awake, and even the eyes actively move under the eyelids. It is believed that during this stage there is a consolidation of memory - the transition of important experiences from temporary to long-term storage.
Unfortunately, the amount of data the experimental authors managed to collect is still not enough to draw serious conclusions based on the differences in the nature of sleep in wild and domestic animals, including humans. Vivien Reicher and her co-authors hope that their work will encourage colleagues to conduct similar experiments, and that in the near future we will have enough information to better understand sleep.
