A steep rise in the number of detentions of mentally unwell people could be a sign that the health service is under "considerable pressure", health inspectors have warned.
In the decade to 2015/16 the number of detentions under the Mental Health Act increased by 40%.
A new review into such detentions by the Care Quality Commission (CQC) found that there were a range of different factors behind the hike.
These include: fewer alternatives to inpatient care in some parts of the country; pressure on bed numbers and population changes - such as more elderly people with dementia.
Meanwhile, better reporting of the detentions may also be behind the rise, as could better awareness of mental health conditions across different professions - such as the police.
CQC said it found "no evidence" that professionals had been misusing the Mental Health Act.
CQC's lead for mental health, Dr Paul Lelliott, said: "There is no single reason to explain why detentions continue to rise every year.
"Population growth, societal changes, better national reporting, duplicate reporting, increased awareness of mental disorder and expanded criteria for detention are all contributing to more and more instances of people being sectioned under the Mental Health Act.
"Some of the factors at play in the rising rates of detention, both nationally and locally, are also signs of a healthcare system under considerable strain.
"Detentions under the Act can be influenced by gaps in support and provision in the system. This includes limited hospital bed availability, which means that people cannot easily be admitted as voluntary patients early in the course of their illness.
"This is a particular problem if it is coupled with limited support for people in the community, which can prevent a person's mental disorder from deteriorating to a point that detention under the Act is necessary.
"It will take more than changes to primary legislation to tackle this fully and to ensure that people with serious mental health problems always get the safe, high-quality and compassionate care they deserve, when, where and how they need it. Changes to the law must happen alongside action to address the wider problems."
In October 2017, the Government announced an independent review into the Act.
Commenting on the report, Labour's minister for mental health, Barbara Keeley, said: "There is no doubt that severe Tory cuts to the community services that intervene before people's mental health reaches crisis point, alongside cuts to other local treatments have contributed massively to the rise in detentions."
Izzi Seccombe, chairwoman of the Local Government Association's Community Wellbeing Board, added: "The increase in detentions is a concern and, as the CQC rightly notes, are indicative of a system that is under strain because of increased demand and reduced funding.
"Councils need adequate funding to enable them to fully play their essential part in the mental health system."