Prolonged bicycling -­which puts pressure on a vital artery and nerve near the genitals can also cause the condition. ED can either have mental or physical causes. Pug said that if the patient has normal morning erections, the ED is likely to be psychogenic, or mental, in nature. However, if a man’s morn­ing erections are poor, his erectile problems are prob­ably due to a physical cause. A patient with ED concerns consulting a doctor should expect to discuss his medi­cal history and go through a physical examination, includ­ing a urine test. Png said that properly prescribed medications such as sildenafil (Viagra) and tadalafil (Cialis) can have an 80 to 90 percent successful response rate with relatively minimal side effects. He discourages the use of alternative medicines that claim to boost male virility, especially if they are not from a reputable source.

He said: “These alternative medicines are not worth the risk when ED can be easily sorted out with a visit to the doctor.”

However, one of the most important factors concern­ing a man’s erection is in the mind. Dr Damian Png, consultant urologist at Singapore’s MD Specialist Healthcare, said: “The brain is the biggest sex organ.

He explained that the brain processes all senses such as the tactile feel of skin or silk, the scent of perfume, melody of music and suggestive sen­sual visual stimuli.

These signals are then sent down the spinal cord and via nerves to the penis, which fills up with blood as a result of blood vessels opening up on stimulation. The penis gets rigid and becomes erect.

An erection thus requires the interaction of a man’s brain, nerves, hormones and blood vessels. Png said common causes of ED include problems related to blood vessels and nerves, such as diabetes, decreased male hormones due to aging and painful intercourse due to a crooked penis. He said that some medica­tion, such as antidepressants and those for blood pres­sure or prostate enlargement conditions, could also cause impotency problems.