Four-month-old babies sleep time due to individual differences, so there is no fixed value, most of the babies sleep time to maintain around 16 hours to 17 hours.
Four-month-old babies sleep time is generally around 16 hours to 17 hours, because as the age of the month grows, the development of the nervous system is maturing, so the sleep time will be slightly shorter compared to the first few months. Parents who find that their baby’s sleep time is short and does not reach 16 hours, but has a better mental state and normal weight gain, generally do not need to be particularly worried.
We can’t generalize the sleeping time of babies, parents just need to provide a better sleeping environment and quality for their babies.