Doctors are warning the Government needs to address how "dangerous working patterns" mean most consultants do not have time off to rest before treating patients after a busy night on call.
The British Medical Association's (BMA) survey of 847 consultants found that nearly three quarters (71%) never have access to rest time following a night on call when their sleep had been disturbed, and a further one in ten (10%) described such rest as rare.
Most (88%) reported being on an on-call rota, with just under half being called to attend hospital during the week, rising to two thirds at weekends.
With the average call-out time at three hours during the week and doubling to six hours at weekends, not having proper rest time compromises patient safety and puts consultants at risk of fatigue and burnout, the BMA warned.
Dr Paul Flynn, chairman of the BMA's consultants committee, said studies have shown that the effects of sleep deprivation on the body are similar to that from drinking alcohol.
He is expected to tell its annual representatives meeting in Liverpool today: "Our concerns about consultants' fatigue and burnout are well founded.
"Sleep deprivation can impair judgment and decision-making, skills that are vital for doctors.
"Studies have shown it can have similar effects to drinking. We would never allow a consultant under the influence of alcohol to treat patients, but continue to turn a blind eye to doctors who are sleep deprived.
"The consultant contract must continue to have robust protections against the acute fatigue that poses risks to patients and the chronic fatigue that risks burnout for consultants.
"With workloads rising and moves to deliver more services out of hours, the Government must make safe working a priority."