My baby only cries in the evening, not during the day—why?

What you're describing—intense distress starting at a specific time in the evening and repeating every day—is really one of the most typical pictures of colic (infantile colic). Colic typically starts when the baby is 2-3 weeks old, peaks at 6 weeks, and usually resolves by 3-4 months. While the diagnostic criteria are often "crying lasting more than 3 hours, more than 3 days a week, for more than 3 weeks," these episodes that hit the same time every evening are very characteristic.

The exact cause is unknown; the most common explanation is that the baby's nervous system is still maturing—they process incoming stimuli all day and in the evening release this accumulated overwhelm through crying. Gas can accompany it, but colic isn't a gas disease; gas usually accompanies it rather than causes it.

Things you can try: gently swaying while holding, swaddling snugly (wrapping firmly), white noise (hair dryer or rain sounds), gentle leg bicycle motions while on their back. Most importantly, this period is hard on you too—stepping out of the room for 5-10 minutes when your baby is safe and crying is completely okay.

If there's fever, vomiting, bloody stools, rash, or failure to gain weight, it's not colic—these would indicate something else. But if your pediatrician has already seen and diagnosed colic and your baby is growing well, you're in the normal course of this condition.