Anyone who has watched a snoozing baby has wondered what’s going on when they smile or twitch in their sleep. Do babies dream? Turns out, we don’t actually know if they dream or not. “We can only know if someone has a dream if they can tell us about it and, of course, babies can’t do that,” says Antonio Zadra, a psychology professor at the Université de Montréal and a researcher at the Center for Advanced Research in Sleep Medicine at the Hôpital du Sacré-Coeur de Montréal.
In adults, we’re most likely to dream during rapid eye movement (REM) sleep, although dreams can happen during other sleep stages, too. This REM sleep may even start before birth: Brain waves that closely resemble those found in REM sleep have been measured inside the womb between 25 and 28 weeks. Since babies spend about half of their sleeping time in REM sleep, some researchers think it only makes sense that they are having some form of dreams. On the other hand, some scientists say that babies are not developmentally capable of the kind of abstract thinking (including the ability to imagine things visually and self-awareness) you need to have dreams.
If babies do dream, their dreams probably won’t have the rich visuals and interactions with other characters that adults have when they dream, says Zadra. “Their dreams are probably very similar to what they experience when they’re awake because they have a preverbal form of consciousness,” he says. “It may be a collection of sensations, whether it’s warmth, suckling on a breast or images of a close-up face.” Just as an adult processes the previous day when they sleep, so does an infant’s brain—it’s just not as advanced yet.
Unlike adults, who are very still during REM sleep, babies may experience these kinds of movements during REM sleep. They are likely part of a baby’s development, as countless new pathways in the brain form and baby learns how to use their muscles and limbs, says Erin Neri, a certified paediatric sleep consultant in Sherwood Park, Alta. For example, researchers at the University of Iowa think that there’s a relationship between a baby’s neck twitches during sleep and their ability to hold their head up. Their research found that once your baby is able to hold that sweet, wobbly head up on their own, the number of neck twitches during sleep drop.
Probably not. The Moro, or startle, reflex, where a baby flails their arms and legs, is a natural newborn reflex that gradually disappears between four and six months of age. “That Moro reflex happens because they don’t have control of their arms and legs yet, but they’re starting to learn,” says Neri. “When it happens at night, it can wake them up.” If a baby cries out in their sleep, it could simply be that they’re processing something that happened that day, like being startled by a loud noise, but it’s not a bad dream as we know it, says Zadra.
Children start reporting dreams at quite an early age, but it’s not always clear if they are referring to dream experiences or things they’ve imagined when falling asleep, says Zadra. Around age four or five, kids are often able to recall scenes or the presence of characters, he says, and studies suggest that a child’s dreams start to resemble those of an adult between five and seven years of age. It makes sense developmentally because dreaming demands fairly high-level cognitive skills. “A person’s sleeping brain has to create this virtual world and put them in it, which requires a sense of self,” says Zadra. “It creates other characters and settings that we interact with, so it’s really quite a complicated task. We probably go about it gradually. We don’t buy a 2,000-piece puzzle for a four-year-old; we buy them a 20-piece puzzle. It’s the same thing with dreams: Our cognitive ability to create these worlds and put us in them takes time and a certain amount of brain maturation to achieve.”
So, go ahead and whisper “Sweet dreams” when you put your baby to bed. Maybe they’re dreaming or maybe they’re not, but the twitches, giggles and cries are likely all part of that super-cool body and brain development that’s going on, even during sleep.