If your 12-month-old baby is waking up with a sweaty head, it may be a sign of overheating during sleep. To prevent this, make sure the room is at a comfortable temperature and avoid overdressing your baby. Using a lightweight sleep sack instead of blankets can also help regulate body temperature during sleep. If you are concerned about your baby's health or have any other questions, it is best to consult with a pharmacist for personalized advice.