What counts as normal night waking? Infant sleep is organized into repeated sleep cycles rather than one uninterrupted block. Babies may briefly arouse between cycles, move, vocalize, or open their eyes. Some return to sleep without assistance, while others signal…

What Happens Between Infant Sleep Cycles Sleep is not a single uniform state. It alternates between non-rapid eye movement sleep, or NREM sleep, and rapid eye movement sleep, or REM sleep. NREM sleep generally becomes progressively deeper, while REM sleep…

Night waking is often normal in infancy Babies are not born with a fully mature circadian rhythm, the internal timing system that helps coordinate sleep and wakefulness across a 24-hour day. In the early weeks, many infants cannot reliably distinguish…

Why Bedtime Changes With Age Bedtime is governed by the interaction of two biological processes. The first is homeostatic sleep pressure, which builds the longer a baby remains awake and decreases during sleep. The second is the circadian rhythm, an…

Why babies make noise during sleep Infant sleep is not a quiet, motionless state. Newborns spend a substantial proportion of sleep in active sleep, a state comparable in some ways to rapid eye movement sleep. During active sleep, breathing may…

What active sleep means in infancy Active sleep is the infant state broadly analogous to rapid eye movement sleep, although the terminology and physiologic boundaries in newborns are not identical to those in adults. It occupies a large proportion of…

Why Sleep Signs Can Be Difficult to Interpret Infant sleep is regulated by interacting biological processes rather than by a single timetable. Sleep pressure builds during wakefulness, while the circadian system gradually develops and helps organize day and night. In…

What sleep pressure means Sleep pressure, also called the homeostatic sleep drive, is the body's internal tendency to seek sleep after time spent awake. It is not a single sensation or a simple countdown. It reflects the combined effects of…

What a Wake Window Means A wake window is the interval from when a baby wakes until the beginning of the next sleep period. Depending on the baby and the context, it may include feeding, diapering, interaction, floor play, transportation,…

Why Iron Matters When Solids Begin Iron is required for hemoglobin synthesis, oxygen transport, cellular energy production, and neurodevelopment. Infants are born with iron stores accumulated during pregnancy, but those stores gradually become less sufficient during the second half of…