Hello. Thanks for following the queries and posting questions here.

Nocturnal erections, as discussed above, are normal physiological responses to the hormone levels in the body. The occurrence of erections in an individual is of some diagnostic value for sexual health practitioners. Based on whether the patient has erections or not, the erectile dysfunction can be categorized into

1)Psychological

2)Physiological

In this test , the subject is asked to wear an elastic device around his penis before going o bed. The device has some properties of detecting information like the diameter and the relays of the penis and is transmitted to a program in a computer. If the nocturnal erection occurs , it is detected by the device and then transmitted to the computer. If there is an erection, the erectile dysfunction is assumed to be from psychosomatic disorder such as depression or anxiety. If not, then it is assumed to be of physiological nature.

Hope this helps.