When a baby who previously slept well suddenly struggles to settle despite being clearly tired, they may be experiencing overtiredness. At this age, nap schedules and wake windows can shift rapidly, and minor adjustments to their daily rhythm can often make a big difference. If your little one is resisting traditional settling methods like nursing or bouncing, it may be helpful to evaluate if their current wake windows are too long, or to consult resources like 'Taking Cara Babies' for guidance on age-appropriate sleep routines.