About 80% of neonatal and newborn sleep time is REM sleep, suggesting a tremendous amount of time dreaming.
https://www.nestedbean.com/pages/your-babys-sleep-cycle
Second, though you both cycle between periods of deep sleep and shorter stints of light REM cycle sleep, your baby does so many more times throughout the night. For you, deep sleep can persist up to 90 minutes at a time. For your baby, it may not last an hour. Therefore, much of his or her sleep is comprised of light sleep, often accounting for more than half of their recommended 13-18 hours of shuteye.
When adults complete a sleep cycle and shift to the next cycle, we might briefly wake up or come close to waking up. The other difference between our cycles and baby's is that when we're shifting from one cycle to the next we might wake up, but we almost immediately fall back asleep. Think about how you’ll barely wake in the middle of the night and shift positions or open your eyes for a split second before falling right back to sleep.
Infants, however, will wake up during that shift and probably need your help to get back to sleep. This skill is learned, and until your baby can fall asleep independently, they won't be able to sleep through the night.
Newborns and adults have very different sleep cycles. So, how does your baby's sleep cycle work? Our newborn sleep cycle chart shows that newborns (babies 0-3 months old), only experience two of the four stages of sleep: stage 3 and stage 4, or REM, and spend about half of their time asleep in each stage.