You might have seen them resting or sleeping in a 24-hour McDonald's outlet near you - slumped over a table, bag by their side.
Some are seeking refuge from noisy neighbours, or the heat in homes without air-conditioning.
Others do not want to impose on their housemates, or are simply trying to kill time on sleepless nights.
The Sunday Times visited six McDonald's outlets to speak to Singapore's own "McRefugees".
REFUGE FROM NOISY NEIGHBOURS
Mr Ng P. L. was sitting alone in a corner of a quiet McDonald's outlet in a polo tee and bermudas, engrossed with his phone, when The Sunday Times spotted him past 1am on a recent weekday.
While the 56-year-old was cagey at first, he broke into a smile when asked what he was doing - he was catching virtual monsters on the popular mobile game Pokemon Go.
The unemployed man is no stranger to the McDonald's outlet near his home in the southern part of Singapore. A few years ago, he spent his nights at the eatery for three consecutive months, although he visits less often now.
"I used to live across the road and my neighbours were very noisy," said Mr Ng in Mandarin. "I couldn't sleep for the past five years."
"After being 'tortured' over these years, now even if I sleep for more than five hours, I wake up with a headache," he said.
While he initially used earplugs to block out the noise, he ended up pushing them too deep into his ear canals, causing an infection.
"Thank goodness there was this outlet. I used to spend time at the void deck of my block and even the police knew me," he said.
Eight months ago, he moved from his old flat to a nearby block but the damage has been done - he suffers discomfort and pain from the inflammation in his sinuses and check-ups have proven too costly.
A chronic lack of sleep also cost him his job as a coffee seller in a school canteen, and he continues to spend some nights at the same McDonald's outlet, still within walking distance from his new home.
"There is air-conditioning, Wi-Fi and even a Pokemon gym nearby," said Mr Ng with a smile.
SLEEPLESS SWELTERING NIGHTS
An elderly man sat by the window, eyes closed, with a bag and a music player the size of a Walkman on the table. He was wearing earphones.
It was 3.30am on a recent weekday.
For the 69-year-old cleaner who wanted to be known only as Mr See, the McDonald's near his home in the east is where he listens to music in the wee hours.
"I wake up around 2am and come out of the house. I can't fall asleep; I get up automatically in the morning," Mr See, who lives with his wife, said in Mandarin. "I've been coming here for a few years. Some old people come here to sleep, but not me," he said. "The coffee shop and market nearby open at 5am, and I eat there before going to work in town."
"Sometimes, when I sit outside, the police will question me and explain that there is a risk of robbery," he said, adding that most other people who spend nights in the eatery are youngsters who are studying.
Retiree Low Kee Tong, 62, whose neck and head would swell after going for kidney dialysis, also spent his nights at McDonald's when he could not fall asleep in his two-room flat.
Pointing to middle-aged men slumped over tables in the Princess Cinema outlet in Bedok, he said many who slept in the store lived nearby in Chai Chee too.
Among those asleep was a man who had spent at least five months in the outlet after losing his flat, due to financial difficulties. He ended up sharing an address with his friend - but only in name.
The man, who is in his 50s, slept with his bags of belongings and did not want to be identified. While he went back to his friend's place every weekend to rest, he spent most nights at McDonald's, not wanting to trouble the man's family.
This Bedok outlet had up to 13 "McRefugees", mostly middle-aged or elderly men, sleeping in its premises, when The Sunday Times visited in May. The outlet closed last month but its former overnight patrons have not taken to another 24-hour outlet in the same area, said staff of the other outlet.
SLEEPING IN A CONSIDERATE WAY
Mr William Lim, 40, was sleeping seated in a McDonald's outlet at around 1am on a recent weekday. He later woke up and took a laptop out of his bag. The self-employed father of three stays there overnight to do work once or twice a week, as he is unable to focus at home.
McDonald's 24-hour outlets allow people to work or rest in a safe environment, he said. "I often see elderly (patrons) who are slumped on a table," he said, adding that staff do not chase them away.
"The people here are quite considerate; we seldom have people who block up a whole row of seats."
'Not common' for people to spend night at McDonald's
A spokesman for McDonald's Singapore said it was not very common for people to sleep overnight in their restaurants.
Mr Faz Hussen, director of communications and government relations at McDonald's Singapore said: "Generally this is not prevalent in our Singapore restaurants."
While all are welcome, he added, he appealed to those who are not eating to be "considerate to dine-in customers who would need the seats", especially in peak periods.
McDonald's has about 130 outlets here, excluding kiosks, and 48 of them are open 24 hours for at least two days a week, said its website.
Other McDonald's staff who declined to be named told The Sunday Times not all 24-hour outlets have people who stay overnight. Those who do tend to leave by around 6am.
Store managers sometimes have to chase such patrons away if they are drunk or cause trouble.
"McRefugees" made headlines in Hong Kong last year when a woman was found dead in a McDonald's outlet in Kowloon Bay.
In Singapore, not many people who sleep on the streets go to 24-hour McDonald's outlets as there might be complaints, said Ms Fion Phua, founder of volunteer group Keeping Hope Alive, which works to meet the urgent needs of the less privileged. "They might go in to use the toilets, or when it is raining very heavily," she said.
Those who sleep outside may also be unwilling to part with their trolleys, which they use to collect cardboard and store belongings. These are hard to bring indoors, or to places with steps and slopes.
They keep to bus stops, void decks or near 24-hour supermarkets instead, said Ms Phua, adding: "When there are more people around, there is a smaller chance they will be pickpocketed.
The Ministry of Social and Family Development (MSF) provided help and support to 300 cases involving the homeless each year on average, from 2005 to last year. Homeless people often go through stressors such as divorce, financial difficulties or health issues, said MSF.
Many sold their flats and spent the money to clear debts or for other purposes, said a spokesman, and some could not live with their families due to strained relationships.
Agencies coordinate help for those at risk of homelessness. There are also welfare homes and shelters for the destitute. The public can dial ComCare Call on 1800-220-0000 or approach an MSF Social Service Office or family service centre if they know of someone in need.
Work is a refuge for deliveryman with no home to return to
With no home to return to, John (not his real name) spends most of his days sleeping on a park bench.
Come nightfall, the 53-year-old McDonald's deliveryman reports for work at an outlet in the south of Singapore. He puts on a smile and banters with customers before zooming off on a company motorbike as orders come in.
Work is his refuge.
This is why he willingly clocks 13-hour days, he told The Sunday Times. After sleeping at a park not far from his workplace, he showers at a shopping mall before work.
After work, he buys breakfast for his mother and spends time with her before catching some sleep outdoors. She lives with his brother's family in a two-room flat.
John, who earns around $1,500 a month, was referred to temporary housing once, but did not feel safe sharing the space with many others.
"Nobody knows what I face," said the father of three, whose oldest child is 24. He has been sleeping on the streets for six years. "But I don't show this to anybody... I joke and laugh, just as normal."
On why he does not live with his relatives, he said: "I don't want to be a burden to anybody."
It was about six years ago, that creditors turned up at his doorstep, saying that he had failed to pay his loan, which he denied.
He had taken a bank loan of $19,000 for renovations, he said. He then borrowed from loan sharks and eventually sold his home. His wife later divorced him.
With no address, he was hauled to court twice for failing to pay fines for traffic offences. He was fined and jailed twice two years ago for up to 16 days. He lost his job of 14 years as a clerk.
Life in the park is rough - at one point, all his belongings were stolen, including his wallet, clothes and documents such as his divorce certificate. Now, he leaves important documents with his relatives.
Police advised him not to sleep in the park, he said. "A park is for people to enjoy, not sleep in... But I have no choice," he added.
Last year, he got into a traffic accident, earning him five stitches above his ear and perpetual headaches. A hospital social worker advised him to get help from the Government and he plans to write to the authorities. He said: "I want to get back what I have lost."