Gaby
Dogs have remarkable abilities, from reading human emotions in faces to an unusual understanding of numbers. Now researchers have evidence of another skill: dogs can listen while they sleep.
How did researchers test this? A small pilot study of 13 dogs found that their brains responded to both dog and human voices even during deep sleep. Ethologist Huba Eleod says this is the first evidence of complex auditory processing during sleep in dogs.
During the study, dogs were connected to devices that recorded brain potentials in response to sounds. Researchers played dog and human vocalizations while the animals were awake, drowsy, and asleep.
Each sound was played at the same volume and lasted about a second. Vocalizations included barking, whining, growling, coughing, laughter, sighing, and yawning. The team avoided harsh or frightening sounds so the dogs would not wake.
Dog sleep is similar to human sleep. As Sciencealert notes, even during the rapid eye movement (REM) phase, dogs seemed able to tell whether a sound came from another dog or from a human, and whether the tone was positive or neutral. This kind of processing has also been shown in primates, including humans, and in non-primates such as mice. Because mammals spend a large part of their lives asleep, the ability to process social signals during sleep may have been important for survival.
How much we understand during sleep depends on the sleep stage we are in and the type of noise we experience. For example, even while asleep our names trigger different reactions compared with other sounds.
Like humans, dogs use sleep to consolidate memories and process emotions. Dog sleep has changed with domestication and more closely resembles human sleep than the sleep of many laboratory animals. Older dogs also experience shallow, fragmented sleep, similar to the sleep disturbances seen in people with dementia.
While more research is needed to confirm these findings, the results add to the growing list of similarities between dog and human sleep. Eleod says this opens opportunities to use dogs in comparative neuroscience studies. Because the tests don’t require training and don’t harm the animals, researchers can use them to study how brains process sounds during sleep. Eleod points out that our most reliable companion animals can help us learn about shared features of mammalian brains.
