Patients brought to Lincoln Hospital by ambulance are being forced to queue in corridors on stretchers because the A and E unit has become so busy.
Calendar was given special Friday night access to the department, where up to 250 patients are being seen every day.
Paramedics say they can wait with patients, on trolleys in hospital corridors, for up to six hours.
Some staff say they are finding it hard to cope and are having to spend their days off sleeping. Hospital bosses are asking the public not to attend the unit unless it is a real emergency.