Field Trials Canada

From the AKC Website
Canine sleeping patterns closely mimic our own, but differ in a key way. When entering sleep, they take about 10 minutes to transition from the slow wave — during which breathing slows, blood pressure drops, and heart rate decreases — into rapid eye movement (REM). In the REM phase, their eyes roll under closed lids, and their body might react to dreams.

Dogs only spend about 10% of their snoozing time in REM because of their irregular sleep patterns. Since they tend to doze off whenever they want, often out of boredom, they also wake up quickly and jump to alertness. As a result, dogs require more total sleep to compensate for their lost REM.

By contrast, humans spend up to 25% of sleep in REM, reflecting their more typical schedule of staying awake all day and resting through the night.

You can read more here.