During trials involving people having Viagra for the first time in their life, patients often reported tiredness. Viagra made them feel they were tired, but in a special way, sexy tired. It was like driving home from work with no stresses hanging over their head, but longing for bed. Some time this overall feeling of tired was accompanied by a stuffy nose, and even uncontrollable erections.

Many have noticed a residual effect to Viagra and doctors explain that this reaction occurs because the brain waves change when one starts going into that relaxed. Then chemicals are released into the brain to facilitate the sleep. This way starts the mechanism of uncontrolled nocturnal erections which is one of the things many male affected by erectile dysfunction are striving to get back.

There are many theories regarding why this happens. Despite of lock of evidences, researches only estimate that is non sexual and probably this 'sexy tiredness' is part of the sleep-repair mechanism of the body. This particular condition slows body activity and spreads more oxygen into the tissues, facilitating health and detoxification.

If this feeling stays active more than an usual tiredness, the situation must be reported to a doctor as a possible side effect of Viagra treatment.