The psychological causes include stress, nervousness and anxiety, worry, depression, and jet lag. There are also a large number of psychological conditions that lead to the occurrence of these symptoms. Some of these psychological disorders include sleepwalking, bruxism or delayed sleep phase syndrome. People who do not follow a regular pattern of sleeping and waking up, are often victims of such psychological disorders. The symptoms, in such cases, are more physical in nature and tend to disrupt the bodily functions.