Taking early retirement is beneficial, at least for your mental health, say researchers.Their study of over 14,000 employees for France's national grid shows giving up work at 55 comes as a great relief to most, cutting stress and fatigue.However, the British Medical Journal study did not find any benefit in terms of physical health.Experts believe the picture is a complex one - other research suggests retirement may worsen health.A large study a year ago found those who stop working completely at retirement age are at greater risk of heart attacks, cancer and other major diseases than those who ease their way into retirement by taking a part-time job.Psychologists say this is because the right type of employment boosts a person's self-esteem and sense of well-being, and hence physical health.It also provides extra cash to feather what can be rather meagre nest eggs.Conversely, staying in a stressful job will have a negative impact.Life transitionIn the latest study, Dr Hugo Westerlund and colleagues at Stockholm University tracked the health of the French employees over a 15-year period that spanned both before and after the workers decided to take up their company's offer of early retirement at around the age of 55.In the year before retirement, a quarter of the workers had suffered from depressive symptoms and around one in 10 had a known medical condition such as diabetes or heart disease.After retirement there was a substantial drop in rates of both mental and physical fatigue, and a smaller but still significant decrease in depressive symptoms.Dr Westerlund said: "If work is tiring for many older workers, the decrease in fatigue could simply reflect removal of the source of the problem."Or it may be that without the demands of work, people no longer notice even when they are tired.Alternatively, retirement might allow people more time to engage in relaxing activities, he said.Ageing workforce"What this research tells us is that we need to do something about the working life itself and change it to accommodate older people if they are to work for longer and in good health."This might mean offering more part-time working or a change in job role, for example.Another factor to consider is whether retirement is voluntary or not.Campaigners have argued that mandatory retirement when a person reaches a certain age is demoralising and discriminatory.Others are forced to carry on working for financial reasons.Michelle Mitchell, Charity Director at Age UK, said: "While retiring early might be beneficial for some people's health, for the majority of people retiring in their 50s simply isn't a financially viable option, particularly with the State Pension Age rising to 66."The UK government plans to scrap the default retirement age of 65 from October 2011.Retirement rules vary across Europe although, even where there is no default retirement age, figures from 2005 showed that people did not, on average, work beyond the age of 65.Source: BBC