Doctors complained of five incidents a day last year where they felt working practices in NHS hospitals were dangerous.
A Mirror probe uncovered more than 1,000 reports including one where a junior doctor was left in charge of more than 40 patients.
Junior doctors are told to lodge “exception reports” with hospital management if they think working practices are dangerous.
The figures lay bare the extent of unsafe wards as the NHS struggles with more than 100,000 posts left vacant. It follows a decade of historically-low NHS funding increases due to Tory austerity.
Freedom of Information responses from 94 NHS Trusts uncovered 1,051 reports logged in 2018. When estimates are made to include the 60 trusts that failed to disclose their incidents, the true total is thought to be around 1,700.
This is an increase of 15% on the previous year, the first that exception reports were introduced.
One doctor at West Hertfordshire Hospitals Trust complained of being left by colleagues to cover at least 40 patients.
He claimed that he was given the work for four doctors, meaning he finished his shift at 10pm instead of 5pm.
A report by a junior doctor of “unmanageable workload” at Salisbury District Hospital said patients with serious symptoms were not reviewed for hours. This included a four-and-a-half hour delay to get to a patient with chest pains.

Another report from University Hospital of North Mid-lands, which covers Stoke-on-Trent, was from a junior doctor who was told to attend patients if they had a heart attack.
The medic was then called to a building four minutes away, on the other side of the site. They wrote: “I would definitely not make it back in time if a patient on west building arrested.”
In Walsall, a junior doctor complained the senior registrar was so rushed that a ward round of 34 patients was carried out in under 30 minutes. This left the junior and a colleague to go round the patients later to do blood tests and write up their notes.
At Rotherham NHS Foundation, a junior doctor on their first day in the job was left in charge of 25 patients. They claimed it was extremely “stressful” and was “unsafe and inappropriate”.
Exception reports note unsafe working hours negotiated by the British Medical Association in 2016 for junior doctors.
The Mirror has been leading the way in exposing shameful NHS conditions, with hard-hitting front page stories on a poorly four-year-old boy forced to sleep on the floor at Leeds General Infirmary and a sick nine-month-old baby having to lie on a chair at the Countess of Chester Hospital in Ellesmere Port, Cheshire.
Sarah Hallett, BMA junior doctors committee chair, said: “Patient safety is of paramount importance, but with staffing at dangerously low levels in many hospitals, the quality of care staff can offer is often compromised.
“This in turn contributes to burnout of junior doctors and puts patients at risk. The exception reports submitted clearly show the immense pressures facing our health service.
“This is not a sustainable way of working as we head into the winter months. It has never been more important for the Government to ensure the NHS has the resources and the
staff that it needs to guarantee the high-quality, safe care our patients need and deserve.”
Paul da Gama, chief staff officer at West Hertfordshire Hospitals NHS Trust, said: “We have strong processes for ensuring our doctors are working
in a safe manner and we have been commended by the BMA.
“Clearly what happened in this instance, which took place nearly 18 months ago, is not acceptable. We carefully monitor safe working practices and can demonstrate that this incident is not representative of the great care we provide for our patients every day.”