Health regulators have imposed sanctions on a West Yorkshire hospital which was keeping patients on a day ward for more than four days and only feeding them with sandwiches and microwave dinners.
The Care Quality Commission (CQC) imposed a legal restriction on Pinderfields Hospital, near Wakefield, after it found that a day unit was being used for longer term care without the adequate resources.
Patients did not have proper washing facilities and were cleaning themselves using disposable cardboard bowls and there were no proper catering facilities, the CQC found after an unannounced inspection.
The CQC said it has imposed an urgent legal restriction on Mid Yorkshire Hospitals NHS Trust, which runs the hospital, preventing it from treating patients in the surgical unit for more than 23 hours.
The CQC said inspectors also found there was no night lighting on the ward so every time a patient was admitted after dark - a frequent occurrence - bright lights were switched on, disturbing the sleep of the other patients.
Patients had no bedside storage so their belongings were left on the floor, a spokesman said.
When inspectors visited the hospital earlier this month they discovered that between July and August "a number" of patients had been on the unit for more than 24 hours and in some cases for more than four days.
Malcolm Bower-Brown, deputy director of CQC in the north, said: "The failings we witnessed on this unit at Pinderfields Hospital were completely unacceptable. CQC took swift action following our inspection to ensure the safety and wellbeing of patients.
"The decision to place an urgent condition on a provider's registration is not one we take lightly. However, when we find poor practice, as we did in this case, we will take immediate action to ensure patients are not at risk.
"We are heartened by the Trust's rapid and positive response to our action and they are working closely in partnership with other agencies to address the issues of concern. However we will continue to monitor the position closely and, if necessary, will not hesitate to take further action to ensure patients receive the service they are entitled to expect."
Stephen Eames, interim chief executive of the trust, said: "We would like to apologise to any patient whose experience on the day surgical unit may have fallen below the high standards we would expect. To our knowledge no patients have come to harm as a result of an inpatient stay on this unit. We do accept that the facilities and environment on this unit were not entirely suitable for inpatients and we are in the process of making significant improvements so it can be used for short stays."