James' Hospital, Leonard et al clearly demonstrated the adverse effects of long shiftwork. After a 32-hour period of duty and only 4 hours sleep a group of 16 interns showed adverse changes in mood disturbance and tests of alertness and concentration. Other studies have shown that loss of sleep rather than long hours is the problem. The quality of sleep is also important and it is inferior when on call, expecting to be woken. Mood and cognitive abilities suffer more then motor skills.
Partial sleep is more harmful than no sleep at all.
Modern on call is much more exacting than it was for previous generations of doctors. Administrators still base their calculations on doctors working half the time that they are on call, whereas the reality is very different. The technology and complexity of present-day acute medicine is immense. The current ventilator resembles the flight deck of an aircraft. It is reasonable to compare the tasks of doctors doing intensive care to that of a pilot.