4 months old baby sleepless, sometimes normal, but sometimes also associated with accumulation of food, lack of trace elements in the body or due to environmental unsuitability and other factors. Common causes and treatment methods are as follows: 1, normal needs: if the baby is hungry or defecate, may appear sleepy, or even cry, should promptly observe the child’s needs, feeding or changing diapers; 2, pent-up food: because the four-month-old baby gastrointestinal tract function is not sound, if eating too much, or eating time and sleep time is short apart, can lead to baby pent-up food, difficult to Sleeping. Parents can give the baby to take lactobacillus tablets to help the baby digestion, at the same time need to pay attention to avoid giving the baby to eat too much, as little as possible before bedtime feeding; 3, lack of vitamin D, calcium: if the baby body lack of vitamin D, calcium, there will be crying and restless, shaking their heads, easy to wake up and other symptoms, lack of vitamin D will also lead to rickets. Parents should take their babies to go outdoors more in the sun, and under the guidance of doctors to supplement the lack of vitamin D, calcium; 4, environmental factors: if the baby’s sleep environment is brighter, the temperature is too hot or too cold, the air is too dry or humid, wet diapers, may lead to the baby feel uncomfortable. Parents should observe the baby’s sleep environment more, check whether the temperature and humidity is appropriate, and keep the room dim, more help the baby to sleep.