Many of my patients ask about the purpose and significance of nighttime erections. This blog will explain those nighttime erections and how they can help differentiate physical from psychological erectile dysfunction.
Men’s early morning erections are a common occurrence and there is nothing to worry about. Most experts will tell you that an erection first thing in the morning is not always due to any kind of sexual stimulus.
So hear are the reasons that men have night time or nocturnal erections.
Reason #1: A man’s rapid eye movement or REM sleep cycle: In a study published in the Achieves of General Psychiatry  researchers found that men characteristically have about five erections every night that is linked to the REM (Rapid Eye Movement) cycle of sleep. It is believed that at this time the brain shuts down a particular pathway to prevent a person from acting out their dreams.
Reason #2: Release of Nitric Oxide: Also tied to the REM sleep cycle, it is believed that when a man is in this stage of sleep, it triggers a cascade of events, and one of those is the release of NO or Nitric Oxide. This compound, causes smooth muscles to relax and blood vessels to dilate which in turn increases the amount of blood that flows into a man’s penis — causing an erection.
Reason #3: Higher testosterone levels in the morning: The amount of testosterone in a man’s body in the morning is far greater than any other time in the day. This normal morning increase of testosterone is also one of the leading reasons for a morning erection.
Reason #4: The repair and restore activity of the body: Scientists also believe that night time or morning erections are the body’s way of maintaining, repairing and restoring the health of the penis. When a man has an erection it causes the erectile tissue of his penis (also known as the corpora cavernosa) to swell, which helps in oxygenating the tissue.
Bottom Line: Night time erections are a good thing and a man should welcome these erections as his friend as it restores the oxygen level to his penis to keep it functioning when he needs those erections to engage in sexual intimacy.
 FISHER C, GROSS J, ZUCH J. Cycle of Penile Erection Synchronous With Dreaming (REM) Sleep: Preliminary Report. Arch Gen Psychiatry. 1965;12(1):29-45. doi:10.1001/archpsyc.1965.01720310031005.
 Diurnal Testosterone Levels in Peripheral Plasma of Human Male Subjects.The Journal of Clinical Endocrinology and Metabolism. JOHN A. RESKO1, and KRISTEN B. EIK-NES DOI: 10.1210/jcem-26-5-573.