The New Economics Foundation said its analysis shows there were 17,500 episodes where stress or anxiety was the primary cause for hospital admission, leading to 165,800 days where beds were occupied due to stress or anxiety in 2016/17.
Episodes where stress or anxiety was a secondary cause amounted to a “staggering” 203,700 cases.
It warned that as more and more people are struggling with the pressures of debt, insecure housing, work instability and a lack of support, this number is only likely to increase.
The think tank said one in 20 English adults surveyed by the charity Shelter said they had gone to their GP in the last five years with a stress-related housing issue – costing the NHS £17.6 million a year.
Meanwhile, 526,000 workers suffered from work-related stress, depression or anxiety in 2016/17, leading to 12.5 million working days lost.
It said this leads to lost output for employers and the self-employed of up to £43 billion a year, and lost tax/national insurance revenue to the public purse of up to £14.4 billion.
Sarah Arnold, researcher at New Economics Foundation, said: “The UK is facing a mental health crisis and it is largely due to our broken economic system.
“As more and more people are struggling with the pressure of debt, insecure housing, insecure work and a lack of support, the number of people dealing with stress and anxiety is only likely to increase.
“We need to build a new economy that works for everyone and allows us to flourish rather than burdening us with stress.”