Hospitals are so full that elderly patients are being discharged in the middle of the night and routine blood tests are being conducted at 3am, the Royal College of Physicians (RCP) has warned.
As bed spaces for acute care become increasingly under demand, patients are being turfed from ward to ward which is leading to a poor continuity of care, the RCP said.
Doctors on wards up and down the country are struggling to care for patients who require urgent or emergency care, according to a damning report, Hospitals On The Edge? The time for action.
As queues at the doors of accident and emergency wards increase, patients who are already admitted to the hospital are shipped from one ward to another "like parcels", to make bed space.
This is leading to fractured care and a lack of compassion that may occur as a consequence, RCP officials said.
A dwindling number of specialist medics working out of hours and staff shortages in key emergency care departments are putting strain on services.
One in 10 consultant posts in emergency medicine are currently vacant, the RCP said.
While the number of patients has increased, the number of beds in general and acute wards has fallen by a third in the last 25 years.
"Hospitals have filled up," said Dr Andrew Goddard, medical director for the RCP workforce unit.
"Many hospitals run a traffic light system for their status: they are green if they are taking in patients; they are amber if they need to be a bit more careful; red for full or black if they are shut.
"What we've seen over the past year or so is that a number of hospitals are on red alert or black alert.
"A black alert used to be a once-in-a-lifetime thing. Now hospitals are on black alert three or four times a year.
"This has been coming on for a while. We have managed to cope with it but the system can't cope much longer, and we need to radically rethink how we provide the care for acute medical patients, particularly the elderly."
Suzie Hughes, chair of the RCP's Patient and Carer Network, said: "I myself had an experience of staying in hospital recently. It was a prolonged stay and I had five different ward changes, all of which took place after midnight.
"All routine blood tests were done at approximately 3am as the junior doctors only had time to do them then.
"It is clearly unacceptable and we need to change things."
The RCP said "radical reorganisation" of the health service is needed if it is to attain high standards of care for patients.
Senior RCP officials suggest that one option could be to shut hospitals, with a bigger focus on community care, so that people could get hospital services at bigger centres 24 hours a day seven days a week.
Professor Tim Evans, lead fellow the RCP's Future Hospital Commission, said: "If we want patients to see compassionate care seven days a week in all specialities and to have their care coordinated by named doctors then it is likely that we will not have the resources to do that on all hospitals sites to the level that we would wish."
If action is not taken, there could be a reproduction of the tragic events at Mid Staffordshire NHS Foundation Trust where as many as 1,200 patients may have died unnecessarily because of poor care.
"There will not be some cataclysmic overnight explosion but there will be a gradual increase in the sorts of tragedies that we've heard about at Mid Staffs," he said.
"All hospital inpatients deserve to receive safe, high-quality, sustainable care centred around their needs and delivered in an appropriate setting by respectful, compassionate, expert health professionals. Yet it is increasingly clear that our hospitals are struggling to cope with the challenge of an ageing population who increasingly present to our hospitals with multiple, complex diseases.
"We must act now to make the drastic changes required to provide the care they deserve."
RCP president Sir Richard Thompson said the research unveils "deep-seeded problems" within acute medical services.
"As I go around the trusts around the country I find a common picture that is of increasing strain on the acute medical services wherever you go in the country.
"If we are going to look at changes in services it is very important that changes are led by clinicians and don't have political intervention.
"One doctor told me that his trust does not function well at night or at the weekend and he is relieved that nothing catastrophic has happened when he arrives at work on Monday morning. This is no way to run a health service. Excellent care must be available to patients at all times of the day and night.
"We call on government, the medical profession and the wider NHS to work together to address these problems."
Alzheimer's Society chief executive Jeremy Hughes said: "People with dementia occupy a quarter of hospital beds, yet constantly we hear that they face poor quality care from staff not trained in dementia care.
"Bearing this in mind, these latest findings are alarming but, unfortunately, not surprising.
"It is painfully evident that the healthcare system stands on the brink of crisis.
"People with dementia are going into hospital unnecessarily, staying in too long and coming out worse. Supporting people to live well at home and reducing the length of time a person stays in hospital can both improve quality of life and save the NHS hundreds of millions per year."
Health Minister Dr Dan Poulter added: "We are modernising the NHS so it can continue to do more and improve care - putting doctors and nurses, those who best understand the needs of patients, in charge of improving the NHS.
"To properly provide dignity in care for older people, we need to see more care delivered at home and in the community.
"Already we are seeing more patients treated as day cases and more patients receiving improved care outside hospitals.
"We are also introducing a new friends and family test, where patients answer a simple question - whether they'd want a friend or relative to be treated in a particular hospital in their hour of need. By making those answers public we're going to give everyone a really clear idea of where to get the best care - and drive other hospitals to raise their game."