It’s been a strong few weeks for furthering our knowledge of our favorite faithful friends. We’ve learned that dogs use facial expressions just for us when they know we’re watching and that they can smell our emotions and then adopt them. Now, we’ve discovered another way dogs are similar to us: they consolidate new memories when they snooze.
In a delightful scientific study, researchers at Eötvös Loránd University in Budapest, Hungary tracked dogs’ brain activity while they snoozed to see if, like humans, dogs use sleep – specifically short bursts of activity called sleep spindles – to retain new information.
Using electroencephalography (EEG) monitors attached to their scalps, the researchers discovered the dogs’ also showed signs of sleep spindles during non-REM sleep. Again, like humans, the frequency of the sleep spindles also indicated how well a dog had retained the new info it learned before its nap. The results are published in Scientific Reports.
Sleep spindles in humans are linked to learning and memory. They only last around half a second and block information from the thalamus, which relays sensory information, from reaching the cortex, where it would be processed properly.
"When sleep spindles happen, the brain is being shielded from outside information, which is very important for memory consolidation because when you want to remember something, you don't want it to mix with outside information," co-author Ivaylo Iotchev told Live Science.
"It's the first time that we can actually show this in a dog," he confirmed.
The researchers used 15 pooch participants across a range of breeds, recording them napping to get a baseline for brain activity. Then they got the dogs to practice actions like “sit” and “lie down” in familiar Hungarian first, and then in unfamiliar English.
After these sessions, when the dogs snoozed, the researchers recorded their brainwaves. After the nap, the dogs repeated the commands, this time just in English, to see how well they’d retained the new info.
Iotchev and colleagues discovered the brain activity looked very similar to that of humans when consolidating memory and experience. Dogs with more frequent sleep spindles performed better, proving they had retained the information more effectively.
Previous studies have suggested that dogs dream, and because humans make up a large part of their everyday experiences, and are one of the main causes of their body’s rewards system, it's quite likely they dream of us.
And dogs sleep a lot. On average, they will dognap for between 12-14 hours a day, and puppies up to 18-20 hours a day. That they're condensing and consolidating all that they learn and experience, just like humans, makes sense.