The FoI request, made by capital-focused business side LondonLovesBusiness.com, revealed a total of 4,700 members of staff had to be given professional help during the period, and causes of stress ranged from anger management to assault, train suicide, near miss and bereavement.
The news comes ahead of London Mayor Boris Johnson's planned closure of 250 ticket offices in the capital, which is expected to save £50m a year.
But TfL described the health and well-being of employees as “extremely important” for any business and “paramount” for an organisation like TfL.
Counselling has been found to be a safe and cost effective way of helping staff who suffer from stress, depression and other issues, and in so doing reducing absenteeism and staff turnover.
It is not the only public sector body where stress is a problem – less than two months ago, another FoI request, by City A.M., revealed mental illness was the most common cause of sick days taken at the Department of Health last year.
This was not reflective of the UK as a whole – the most recent data from the Office of National Statistics put mental health in third place as a cause of sick days taken, falling behind muscle problems and minor illnesses such as coughs and colds.