Why does 4-month-old baby wake frequently at night?

Frequent nighttime waking in 4-month-old babies is quite common and usually related to a developmental turning point. During this period, babies' sleep cycles begin maturing; like adults, they transition between light and deep sleep, but haven't yet fully learned to fall back asleep on their own through these transitions. Also, the "sleep regression" often seen around the 4-month mark means babies become more aware of their surroundings, and nighttime waking may increase. This isn't an illness—it's a natural part of brain development. Hunger, teething signs, or gas may also contribute to frequent waking. Current pediatric opinion suggests that establishing a consistent bedtime routine and allowing short opportunities for baby to self-soothe during transitions can be helpful. If waking becomes very frequent and affects baby's daytime mood or weight gain, consulting your pediatrician is worthwhile.