Testosterone, the male hormone, peaks in early adulthood and declines steadily thereafter. The drop in testosterone among men in their forties is around 1% every year.
A number of men can function as they did even with lower levels of testosterone, but it is often linked to changes such as increased anxiety or stress, poorer sleep, loss of strength and decline in sexual function.
The Ageing Male Symptoms framework is a great way for a man to analyse this impact. It is a clinically researched questionnaire that can help men understand the changes they are going through on three dimensions--psychological, somatic and sexual--and typically takes less than seven minutes to complete.
An advantage of taking the AMS assessment here is that you get to see how you are doing on various dimensions of ageing vis-a-vis other users who have taken the same assessment.Take the Ageing Male Symptoms assessment