Whether they wake every two hours or nap like a boss all day long, one thing’s for sure: Babies’ sleep cycles are unique compared to adult sleep cycles. Discover a few of the differences—as well as similarities—between the way you and your baby sleep.
Of course, there’s the obvious: Newborns sleep 10 to 18 hours per day, more than any other age group. The next-best group of sleepers—infants over three months—sleep nine to 12 hours per day, plus naps. In comparison, American adults average less than seven hours of sleep per night.
Adults cycle through sleep in various stages of rapid eye movement (REM) and non-rapid eye movement (NREM), with NREM sleep divided into four stages. Adults spend about 20 to 25 percent of the night in REM sleep, and each sleep cycle takes about 90 to 120 minutes. In babies, meanwhile, the sleep cycle is more evenly divided between REM and NREM sleep. Furthermore, baby sleep cycles are shorter, lasting only about 50 minutes for the first nine months of life.
In REM or “active” sleep, an infant’s brain is developing, consolidating, and solidifying various cognitive and physical skills. Similarly, adults in REM sleep have active brains as well; this is when your mind is processing the day’s events, forming memories, and releasing serotonin.
While many adults sleep straight through the night—perhaps waking once—because a baby’s sleep cycle is so short, he or she is prone to fully or partially waking up during the transition from deep sleep to light sleep. The good news: Most infants learn to self-soothe and send themselves back to dreamland. Infants are also more easily awakened when they first fall asleep during the active REM stage. During NREM’s “quiet” sleep stage, infants are less likely to be woken up (similar to how adults are less likely to awaken during deep sleep).
As a baby grows, the sleep cycles will start to look more and more like an adult’s version. Less and less time is spent in REM sleep while simultaneously the sleep cycle itself lengthens. Eventually, by school age, your child will be sleeping in cycles of 90 to 100 minutes.