The poor state of London's health was revealed on Wednesday by figures showing that one third of Londoners get between four and six hours of sleep a night.
A survey published by the Nuffield Health found that nearly four in ten (38 per cent) of Londoners had called in sick at work because of their mental health at least once in the past year, higher than the national average.
More than 2,000 Londoners were surveyed as part of Nuffield's Healthier Nation Index, a comprehensive annual survey tracking changes in exercise habits and general health across the UK.
Nearly half of those surveyed (46 per cent) in the capital felt their sleep quality had got worse in the past year, while 44 per cent said they sleep less.
Scientists recommend that young people and adults sleep for at least eight hours a night to prevent long-term health issues.
Work was found to be a significant barrier for Londoners (48 per cent) to do exercise than for the rest of the nation, while more than two-thirds (36 per cent) of people in the capital said looking after children was a barrier, higher than the national average of 29 per cent.
Londoners were also found to be more likely to experience loneliness than the rest of the UK, with a quarter of respondents naming a lack of meaningful relationships.
Pooja Kumari, Senior Public Affairs and Policy Manager at Nuffield Health, told the Standard: "London offers so many opportunities for our career and social life, but it can also really take its toll on our mental health.
"Many Londoners are grappling with feelings of loneliness and isolation. And I think those are factors which can be compounded by reduced access to green space and nature or air pollution, which can all exacerbate stress and anxiety."
However, the survey also found that Londoners were five per cent more likely to exercise in the gym than the national average and four per cent more likely to play team sports.
Hillingdon was found to be the most active borough with residents exercising for an average of 102 minutes, followed by Merton and Islington.
Londoners with a higher average household income were far more likely to exercise regularly, according to the survey.
Ms Kumari said: "For Londoners, cost is a huge barrier to exercise. So whilst it is encouraging to see that people are more active, it is clear that more needs to be done to overcome these barriers."
She added that employers could play a "huge role" in helping to combat poor health by encouraging employees to exercise and take care of their mental health.
"Companies that go above and beyond to support their employees will have a happier, healthier and ultimately more effective workforce," she said.
