It is normal for men to experience erections without any form of stimulation. The random erections are very common among adults and adolescents. The erections are often experienced when one wakes up early in the morning. Here are some of the common causes of the random erections.
First and foremost, erections often occur when you think about someone or something sexually exciting. The brain normally sends signals to that make the arteries connected to your penis to allow more blood to flow to the region. The veins carrying blood away from the penis region often shrink. This leads to the swelling and stiffening of the penis hence leading to an erection.
Erections can also occur because of other causes besides sexual stimulation. Nocturnal penile tumescence can occur because of the changes in the hormonal balance. The changes can be caused by physical stimulation from getting in contact with your sheets or other reasons.
A healthy man often experienced three to five orgasms per while he is deeply asleep. Each of the erections can last between 25 to 35 minutes. The levels of hormones often fluctuate in the course of the day especially the testosterone, which tends to cause random erections.