For many of her patients, the woman they call "Sister Gali" is closer than family. She tends to their daily needs, listens to their woes, puts up with their unpredictable ways and - when she can - sees them off on their final journeys.
With nearly 40 years at the Institute of Mental Health (IMH), Ms Therese Ann Galistan, 62, is one of the longest-serving nurses at the hospital, which recently held a media tour.
Ms Galistan, who is single, is one of a rare breed, for psychiatric nursing is not popular among young nurses because of its many challenges.
It is not unknown for patients to get into fights, injuring staff or one another.
Once, a patient climbed onto the hospital's roof. Ms Galistan and her colleagues spent more than an hour coaxing the man to come down.
"Sometimes, there are aggressive or violent patients, and you need to recognise the early signs and take preventive action," she said.
She has had to restrain patients but has never put one in a straitjacket - it has not been used here since the 1930s.
Like most people, Ms Galistan initially felt fearful about working at the mental hospital, but learnt to take it in her stride.
Ms Galistan, one of six children in a family with traces of Armenian ancestry, is driven by the desire to help others, like her mother and grandmother, who were teachers.
"I always admired people serving the community - people wearing uniforms," she said. "I wanted to be a policewoman at first, but I didn't meet the height requirement," she said.
Her mother suggested that she try nursing and she was posted to IMH, then Woodbridge Hospital, as a student nurse back in the 1970s.
Her encounter with a depressed woman there made her choose a career in psychiatric nursing.
"Every day, I would spend time talking to her and telling her she could trust me. But she was totally unresponsive - no eye contact," said Ms Galistan. "All my other colleagues were making progress."
But the trainee nurse did not give up and was rewarded when the patient improved after therapy. The next time the patient saw Ms Galistan, she ran to her and gave her a kiss.
"She knew I was trying to help, and I knew that I had an impact on her."
Ms Galistan returned to IMH as a psychiatric nurse in 1975 and has been there ever since. As a junior nurse, her daily routine involved feeding, bathing and helping patients change.
Now, as a senior nurse clinician with the hospital, she has a more supervisory role although she also takes care of elderly patients.
Many of them have a mixed bag of ailments - dementia, for instance, coupled with schizophrenia or bipolar disorder.
Dementia patients are sometimes taken to a garden with a special looping path at IMH's new dementia ward. The path allows dementia patients to satisfy their urge to wander and yet ensures that they do not get lost, as they walk but do not end up going anywhere.
Sadly, many patients do have nowhere to go to, as their families have effectively abandoned them and left them in long-stay wards.
Even for the short-stay patients, being admitted can be harrowing. This is why Ms Galistan feels it is important to make the environment as homely and comfortable as possible.
"We are family to them, because they can't go home," she said.
Despite the occasional violent patient, Ms Galistan has never thought of quitting.
And her job has its "cute and funny" moments - like the time she slipped and a male patient stopped her from falling.
"He thought he had saved my life," she said. "He asked: 'Do you think we should get married?'"
Ms Galistan remembers the days when IMH was still Woodbridge Hospital - spread out over 145ha instead of its current 25.
"We went gardening with the patients, we flew kites, we played games like rounders and badminton," she said. "At night, you could hear owls hooting."
The increased administrative workload has meant that she now has less time with her patients. Her heart for them, however, remains unchanged.
"Knowing I can make a difference to their lives and having them affirm me - it's very gratifying," she said.