There is something strangely disquieting about standing in a padded cell – focusing on the tiny chink of light coming through the slatted window in the equally padded door; imagining the distress and confusion that must have once surged through the patients at the Glenside psychiatric hospital when they found themselves locked in one of these padded rooms.

But treatments we may perceive as brutal today were once believed to be progressive.

The hospital began life in 1861, when it was opened with the no-nonsense title of the Bristol Lunatic Asylum. It's a name that may seem jarring to modern sensibilities, but the public perception of psychiatric health hasn't always been as enlightened as it is today, as Dr Ihsan Mian explains as he shows me around the newly refurbished exhibition.

The consultant psychiatrist worked at the hospital – and other psychiatric units across Bristol – for more than 30 years, until his retirement in 1998.

When the hospital finally closed its doors in 1994, more than a century of artifacts were brought together to tell the story of the evolution of psychiatric treatment.

At its height in the 1950s Glenside was a sprawling facility, with up to 1,600 patients.

The hospital museum – one of only three museums devoted to the subject in the country – was founded by the late Dr Donal Early, an eminent psychiatrist who was based at the Stapleton hospital for 35 years until 1979.

"When the hospital closed we moved the museum into the neo-gothic former hospital chapel next door," Dr Mian explains, as he leads the way through the museum at the Blackberry Hill site, which is now occupied by the University of the West of England's Glenside Campus.

Today, Dr Mian, the current chairman of the museum, recalls his time serving in the Victorian corridors of the hospital alongside Dr Early with pride and affection.

"Dr Early was a great, great man," he says. "His progressive work was famous worldwide."

In fact, Glenside always had a reputation as a place of scientific progress. When it opened its doors in 1861, as the Bristol Lunatic Asylum, it was a model of enlightened thinking, in comparison with the city's previous mental heath provision – two wards in the Tudor St Peter's Hospital, which was located in what is now Castle Park.

Part workhouse, part lunatic asylum, St Peter's had become grotesquely over-crowded by the mid 19th century. The St Peter's building, which was later destroyed in the Blitz, may have looked grand on the outside, but inside conditions were poor.

The ordered and pristine wards of the new Bristol Lunatic Asylum would have been a remarkable contrast for the medical staff of the era.

"When it was first opened, it was dictated that strait jackets should not be employed in the new hospital," Dr Mian explains, as he shows me a case containing a strait jacket from the period.

"That was certainly progressive for the time. But many of these patients were severely disturbed, and without shackling them, there was a danger of patients injuring themselves. That's how the first padded cells came into use here.

"They may have a sinister reputation now, but actually padded walls were there for the patients' own protection. They were still being used to some extent during my early career, though later, as medication and staffing levels improved, they eventually became unnecessary."

There are more grisly exhibits on show – including original Electro- Convulsive Therapy (ECT) machines, which used controversial electric shock treatment, administered directly into patients' brains.

Dr Mian says ECT is another much-maligned element of psychiatric history.

"These days, such direct physical treatments have been gradually superseded by a greater reliance on medication or counselling – with various kinds of talking therapy and occupational therapies employed for a range of conditions.

"Only very rarely is ECT now administered. But I have certainly prescribed it earlier in my career. It does work in the most extreme cases of psychotic depression.

"There was one elderly lady I administered it to, who would not eat because of her extreme depression, and so the ECT became a way of saving her life.

"I still say today, if I became psychotically depressed to that level I hope somebody would have the courage to administer ECT to me."

There are other grisly areas of the exhibition, which may be best avoided by young children or those of a nervous disposition – such as a section devoted to lobotomies and an area that recreates the hospital morgue. But the message throughout is to educate and enlighten visitors about psychiatric medicine.

The museum was closed in 2008, after safety checks found that the wiring in the 1881 chapel was unsafe. The landlord – the University of the West of England – has since invested more than £40,000 in making the building safe.

During the rewiring, the team of 10 volunteers who run the museum took the opportunity to completely redesign and rebuild the exhibition.

"Originally when we came here, we literally exhibited items in rows on the church pews," Dr Mian says. "But now we have been able to install proper exhibition spaces, which we hope will allow us to educate more people about the history of psychiatric care on the site."

The Glenside Hospital Museum is open Wednesdays and Saturdays, from 10am to 12.30pm. Admission is free. For more information, visit www.glensidemuseum.org.uk.