One and a half month baby crying at night may be related to physiological factors such as hunger, environmental discomfort and pathological factors such as rickets and gastrointestinal diseases. 1. Hunger: if a one and a half month old baby is hungry at night and does not get fed in time, he or she will cry. 2. Environmental discomfort: low environmental temperature, strong light, the presence of noise, etc., can also affect the sleep of one-and-a-half-month-old babies, causing the phenomenon of crying. 3. Rickets: one and a half month baby crying at night may also be caused by vitamin D deficiency. 4. gastrointestinal diseases: if a half month baby suffers from gastrointestinal diseases such as colic, intestinal spasms, etc., also easy to cause night crying phenomenon. A month and a half baby crying at night may also have other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.