A rise in the use of zero hours contracts could be contributing to poor mental health among younger people, a new study suggests.
Young adults who are employed on the controversial contracts, under which they do not know if they have work from one week to the next, are less likely to be in good health and are at higher risk of poor mental health than workers with stable jobs.
Researchers from the Centre for Longitudinal Studies at the UCL Institute of Education analysed data on more than 7,700 people living in England who were born in 1989-90.
A total of 5% had zero hours contracts.
Researchers found that those employed under zero hours contracts were 50% more likely to report poor mental health than those in more secure employment.
The unemployed and shift workers were also more likely to report mental ill health.
Meanwhile, compared to those who were not on such a contract, having a zero hours contract reduced the odds of reporting good health by 41%.
"More people than ever are working on zero hours contracts in the UK, and this new data shows this to be contributing to poorer mental health among younger workers," said Craig Thorley, senior research fellow at the Institute for Public Policy Research.
"Efforts to improve the UK's mental health must recognise the important relationship between health and work.
"Government and employers must work together to promote better quality jobs which enhance, rather than damage, mental health and wellbeing.
"Without this, we risk seeing increased demand for mental health services, reduced productivity, and more young people moving on to out-of-work sickness benefits."
The lead author, Dr Morag Henderson, added: "Millennials have faced a number of challenges as they entered the world of work. They joined the labour market at the height of the most recent financial crisis and faced higher than ever university fees and student loan debt.
"There is evidence that those with a precarious relationship to the labour market, such as shift workers, zero hours contract holders and the unemployed are more at risk of poor mental health and physical health than their peers.
"One explanation for these findings is that financial stress or the stress associated with having a low-status job increases the risk of poor mental health.
"It may also be that the worry of having no work or irregular work triggers physical symptoms of stress - including chest pain, headaches and muscle tension."
Previous data has shown that 905,000 workers in the UK were employed on zero hours contracts in their main job between October and December 2016.
People on zero hours contracts are more likely to be young, part-time, women, or in full-time education when compared with other people in employment, the Office for National Statistics (ONS) reported in March.
On average, someone on a zero hours contract usually works 25 hours a week. Around one in three of these people want more hours, the ONS said.
Commenting on the study, TUC general secretary Frances O'Grady said: "If you don't know how much work you will have from one day to the next, this is bound to impact on your health and mental well-being.
"People need decent jobs they can build a life around. It's why the TUC is calling for a ban on exploitative zero hours contracts.
"Employers must not be allowed to get away with treating workers like disposable labour."
A spokeswoman from the Department of Business, Energy and Industrial Strategy said: "We are committed to building an economy that works for everyone and making sure employment rules and rights keep up to date to reflect new ways of working.
"That's why we asked Matthew Taylor in October to conduct an independent review into modern working practices.
"As part of his review, Matthew has been looking at different ways of working and well-being in work as part of the review, which we expect to be published shortly."