They came in their dressing gowns and slippers - some even carrying fluffy hot-water bottles. Hundreds of pupils from schools across Aberdeenshire took to cardboard boxes for the night to raise awareness of and cash for the homeless.
The Sleepout is organised every year by the charity The Cyrenians, and since the event was first launched in 1991 it has raised more than Pounds 300,000.
While freezing fog blanketed the city, hundreds of pupils, teachers and families took shelter in the boxes and sleeping bags in the arena at Aberdeen Exhibition and Conference Centre. Some hardy souls braved the elements in the car park in the open air.
As well as raising money, the aim was to let people experience what it might be like to be homeless and have to sleep rough. There was a party atmosphere as the event got underway, with music in the main arena and deliveries of pizza to keep spirits up.
These youngsters know it's not this much fun when you're really homeless. And they're also getting the message about how the other half lives in a city known for its affluence, but where homelessness is on the increase.
Twelve north-east schools took part, including pupils who travelled with their teachers from Fraserburgh and Banff Academies.
Modern languages teacher Claire Bradford accompanied 45 pupils from Torry Academy, but remembers taking part as a pupil at Mackie Academy. "I really enjoyed it as a pupil because you get a night away and you get to have fun with your friends and meet people from other schools - as a teacher, it's possibly less fun than when you were 15," she laughs. "But it's nice to see the kids in a different situation and it's good to see them doing so much work for charity."
Torry Academy pupil Derek Muirhead, 13, created his own cardboard box home, but seemed far too excited to sleep in it. "I am doing it because it's good for charity and it's fun," he said as he curled up in his sleeping bag.
Fifth-year Jessica White was colour co-ordinated with a pink sleeping bag and matching track-suit - even her fluffy hot-water bottle cover was pink. "The last few times I've wanted to do it but I never had the courage and preferred my bed instead. Today, I decided to just go for it and help raise more money."
Watching them prepare for a long night was Paul Hannan, chief executive of The Cyrenians. The charity was delighted so many youngsters turned up. "Often, young people get a really negative press and to see some 1,000 young people turn up for an event like this - it really is amazing," he said.
Mr Hannan is concerned at the growing number of people becoming homeless in Aberdeen - some of whom are as young as the pupils on the sleep-out. "There's a fairly significant number of 16 to 17-year-olds who become homeless. Some of that is linked to youngsters who have been looked-after or accommodated by local authorities."
"But there are quite a lot of young people who have been having a hard time at home and once their 16th birthday comes, parents can say, `Well, on you go then', and some of them go at that point.
"But when you look at some of the things that these young people are experiencing, some of the stories that people tell us . where it's their parents who are drug dealers and the parents provide them with drugs, and then if they are trying to do something about their drug habit, they can't obviously go home.
"Some parents we are aware of are also sending them out to prostitute themselves as part of getting money for drugs. So where society thinks of parents as protectors, it's worse than that - people are exploiting their own children. There are some very, very sad cases."