People are sad at night may be caused by bad mood, depression, anxiety, etc., but also may be related to personal sentimental character. 1, bad mood: If the patient has recently suffered any changes, such as lost love, unemployment, the death of a loved one, arguments with friends, or isolated in life, wronged, etc., something bad has happened. In the daytime there may be work, life and other things to distract, at night alone will be repeatedly recalled, it will be more sad; 2, depression: If the patient did not happen bad events, suddenly a long period of inexplicable sadness, may be due to depression, is the disease caused by melancholy, sadness, more negative about everything, should promptly seek medical attention; 3, anxiety disorders: If the patient is sad at night , accompanied by panic, palpitations and other symptoms, may be due to anxiety disorder, similar to depression, are disease caused by mood changes, should promptly to the psychology department for intervention; 4, personality factors: some people have a delicate mind, sentimental, in the dead of night will feel lonely, there will be a feeling of sadness. If you have previously seen the plot sentimental novels or television, will be more sad, this and the patient’s personality, and not due to disease; 5, other: insomnia patients to the night is easy to tension, fear, worry about sleep at night, will be very sad, pain.