Babies with Down syndrome often appear sleepier during the day, but they typically get less total sleep than other babies, not more. Research comparing children with Down syndrome to typically developing peers found they slept about 55 fewer minutes at night and 38 fewer minutes overall per 24-hour period. The daytime drowsiness that many parents notice is usually a sign of poor-quality nighttime sleep rather than a higher need for sleep.
Why They Seem Sleepier but Sleep Less
The pattern is easy to misread. Babies with Down syndrome do nap more during the day, roughly 21 extra minutes on average compared to peers. But that extra daytime sleep doesn’t make up for what they lose at night. Their nighttime sleep is shorter, more fragmented, and lighter in quality. So while it can look like your baby is sleeping a lot, the total amount of rest they’re actually getting is often less than you’d expect for their age.
Parents of children with Down syndrome report sleep problems at more than double the rate of other parents: 45% versus 19% in one study. These problems include frequent night waking, snoring, and difficulty settling independently.
What Disrupts Their Sleep
Several physical features common in Down syndrome work together to make sleep harder. Low muscle tone (hypotonia) affects the muscles that keep the airway open during sleep. Combined with a smaller upper airway, a relatively large tongue, and differences in the shape of the mid-face and jaw, this creates conditions where the airway can partially or fully collapse during sleep. The result is obstructive sleep apnea, where breathing repeatedly pauses or becomes very shallow throughout the night.
Sleep apnea is remarkably common in these babies. In one study of 40 consecutive infants under 12 months who were tested with a formal sleep study, every single one met the criteria for obstructive sleep apnea. Among infants under 6 months referred for breathing symptoms during sleep, 71% had severe sleep apnea. These aren’t numbers from a highly selected group of sick babies. The condition is so prevalent that the American Academy of Pediatrics recommends a sleep study for all children with Down syndrome between ages 3 and 4, regardless of whether parents notice symptoms, because parent reports often miss the problem.
Iron deficiency, which is more common in Down syndrome, can also contribute to restless legs and periodic limb movements during sleep. These involuntary movements disrupt sleep further, and the resulting poor rest can show up during the day as hyperactivity or inattention rather than obvious tiredness.
Their Sleep Architecture Is Different
Even setting aside breathing problems, the internal structure of sleep in babies with Down syndrome differs from typical development. EEG studies show these children wake more often during the night, spend less time in the deepest stages of sleep, and get less REM sleep (the stage linked to brain development and memory consolidation in infants). They also shift more frequently from deeper sleep stages to lighter ones, meaning their sleep is less stable overall.
Interestingly, their circadian rhythms, the internal body clock that regulates when you feel awake and when you feel sleepy, develop on a normal timeline. The issue isn’t that their bodies don’t know when to sleep. It’s that once they’re asleep, they can’t sustain the deep, restorative stages as well.
Why Sleep Quality Matters for Development
Deep sleep and REM sleep are when the brain consolidates learning, processes new motor skills, and strengthens neural connections. For a baby already navigating developmental differences, losing time in these stages can compound the challenge. Poor sleep efficiency doesn’t just mean a tired baby. It can affect cognitive development, motor learning, and behavior in ways that are easy to attribute to Down syndrome itself rather than to a treatable sleep problem.
What Parents Can Do
The AAP recommends discussing sleep-disordered breathing symptoms with your pediatrician within the first six months of life. Signs to watch for include heavy or noisy breathing during sleep, snoring, unusual sleep positions (like sleeping with the neck hyperextended to keep the airway open), frequent night waking, and pauses in breathing. Many parents assume snoring in their baby is normal or harmless, but in Down syndrome it’s a red flag worth investigating. About 19% of parents report snoring, compared to just 2% in typically developing babies.
One factor that explained a surprising amount of the sleep difference in research was parental presence at bedtime. When parents stayed with their child while they fell asleep (room-sharing was reported by 37% of Down syndrome families versus 17% of controls), nighttime sleep was significantly shorter. This doesn’t mean room-sharing causes poor sleep on its own, but helping your baby learn to fall asleep independently, when developmentally appropriate, can make a meaningful difference.
If a sleep study confirms obstructive sleep apnea, the most common first-line treatment for older infants and toddlers is removal of the tonsils and adenoids. However, because of the underlying anatomy in Down syndrome, this doesn’t always resolve the problem. About 55% of children with Down syndrome who had the surgery still needed a breathing support device at night afterward, and 18% needed supplemental oxygen. For babies too young for surgery or those with persistent apnea, a small mask that delivers gentle air pressure during sleep can keep the airway open. Children with Down syndrome sometimes need a version that provides different pressure levels for breathing in and out, since they tend to have breathing patterns that a standard device doesn’t fully address.
The core takeaway: if your baby with Down syndrome seems excessively sleepy during the day, that’s not a sign they’re getting plenty of rest. It’s often the opposite. Bringing it up with your pediatrician early, and pushing for a formal sleep evaluation if symptoms are present, can lead to treatment that improves not just nighttime sleep but daytime alertness and development.