When a newborn or infant cries persistently and is difficult to soothe, particularly during the evening hours, parents often describe the experience as nighttime fussiness. This behavior is a normal form of communication because a baby cannot yet articulate their needs or discomforts in any other way. Understanding the common underlying causes can transform a confusing and stressful nightly ritual into a manageable process of identifying and addressing the baby’s specific concerns.
Basic Comfort Needs
The first step in addressing nighttime fussiness involves a quick check of the baby’s most immediate physical needs. Hunger is the most frequent culprit, even if the baby was recently fed, due to their small stomach capacity and rapid metabolism. A baby’s sleep cycle is often short because they need to refuel after only a couple of hours.
Another easily resolved cause is a soiled or wet diaper, which can cause significant skin irritation and discomfort. Check the baby’s temperature; babies are highly sensitive to thermal fluctuations and may fuss if they are too hot or too cold. The ideal ambient temperature for a baby’s sleep environment is generally between 68 and 72 degrees Fahrenheit. These simple checks eliminate the most fundamental reasons for distress.
Gastrointestinal Discomfort
Internal digestive issues are a common cause of evening fussiness, often peaking as the day winds down. Gas discomfort results from the immature digestive system processing milk sugars and air swallowed during feeding or crying. Simple techniques like gently moving the baby’s legs in a “bicycle” motion or performing a firm, upward belly massage can help trapped air pass.
Reflux, where stomach contents flow back up into the esophagus, can cause crying and arching of the back during or immediately after a feeding. This sensation, sometimes described as heartburn, may lead a baby to pull away from the breast or bottle in discomfort. If a baby cries for three or more hours a day, for at least three days a week, for three or more weeks, they may have colic. Colic typically peaks around six weeks of age and resolves by three to four months. Although the exact cause remains unknown, it is often associated with evening episodes of intense crying that do not respond to typical soothing methods.
Sleep Schedule and Environment
A common cause of nighttime fussiness is overtiredness. When a baby stays awake too long past their age-appropriate window, their body releases stimulating hormones like cortisol and adrenaline, which makes it difficult for them to settle down for sleep. This state of “wired but tired” leads to crying and resistance at bedtime, as their system is overwhelmed.
Conversely, a baby may be undertired if they have not built up enough “sleep pressure” during the day, causing them to resist falling asleep. Establishing a consistent, predictable bedtime routine signals to the baby that the day is ending, which aids in the transition to sleep. Optimizing the sleep environment is also important, which includes using a dark room to promote melatonin production and using consistent white noise to mask household sounds.
Developmental Phases
Some bouts of fussiness are temporary and related to natural developmental milestones. Growth spurts, which commonly occur around two to three weeks, six weeks, and three months, often result in increased hunger and the need for cluster feeding. During these periods, a baby may want to feed almost constantly in the evening.
The “witching hour” describes a period of unexplained, intense fussiness that occurs most reliably in the late afternoon or early evening, typically between 5:00 and 11:00 PM. This phase begins around two to three weeks, is most severe at six weeks, and usually resolves by three to four months of age. This is likely due to a combination of overstimulation and an immature nervous system struggling to regulate itself at the end of the day. For older babies, starting around seven to nine months, separation anxiety can cause nighttime waking and crying as they become aware of a parent’s absence. This is a normal cognitive milestone.