Broadmoor Hospital has been told to make urgent changes after a report which highlighted the “overuse” of face-down restraints on patients.
The CQC rated the high-security hospital in Berkshire “inadequate” after an inspection.
Inspectors said low staff levels and low morale were affecting safety and the quality of services.
The hospital’s trust said it had been rated “good” in many other areas but pledged to make improvements.
West London Mental Health NHS Trust was told it must improve its practices in relation to the use of restraints and seclusion, which was an issue across the trust.