Worries about the recession could lower testosterone levels among men, a doctor has warned.

Dr Richard Petty, who works at a private clinic for men, said that chronic stress caused by financial worries, redundancy or working longer hours may cause levels of the hormone to drop.

Testosterone is associated with sexual function, circulation and muscle mass, as well as mood, memory and concentration.

"When a man becomes grumpy or irritable, it's easy to blame work or simply the effects of ageing," The Telegraph quoted Petty as saying.

"In the short-term, stress can increase levels of testosterone and this is useful to help people respond quickly to pressures and new situations. But chronic stress, which is ongoing, is a major factor in the decline of testosterone," he cautioned.

"Chronic stress occurs all too frequently due to our modern lifestyles, when everything from high-pressured jobs to unemployment keeps the body in a state of perceived threat," he added.

Lower levels of the hormone can cause irritability, lethargy, low sex drive and a lack of concentration.

Petty has suggested that men should reduce their stress levels as much as possible by getting enough rest, eating healthily and exercising.