San Francisco,  SoftBank-backed digital mental health company Cerebral is laying off about 20 per cent of its staff as it restructures its business.

According to The Wall Street Journal, nearly 400 people will lose their jobs, primarily clinical staff and care counselors.

A memo from its CEO, David Mou said the cuts would affect employees across the company, including at headquarters and among clinical care staff and support workers.

"The changes are part of Cerebral's ongoing transformation programme, which drives to create more sustainable growth and stability, while further delivering our mission to democratise access to high-quality mental health care for all," a Cerebral spokesperson was quoted as saying in reports.

"These changes are focused specifically on realising operational efficiencies while prioritising clinical quality and safety across the organisation," the spokesperson added.

The care counselors meet patients regularly to manage medications prescribed by clinicians and provide support.

The company has come under scrutiny for making it easier to provide Attention-deficit hyperactivity disorder (ADHD) medication to potential clients.

In April, a former Cerebral executive sued the company, alleging he was fired after voicing concerns about unethical prescribing practices and patient safety issues.

The San Francisco-based company has raised more than $426 million to date, and was last valued at $4.8 billion.

Earlier this year Cerebral laid off "hundreds" of people, primarily affecting its support and operations team to improve its programmes.