Working on the late night shift - is it doing damage to your health?
While the nation is tucked up in bed, an often unseen army is keeping the country ticking over.
Three people who work through the nocturnal hours discuss how it impacts their life.
Whether it's manning the hospitals and emergency services, preparing offices and shops for another day of trade, plying food and drink to revellers or simply providing entertainment to insomniacs, the night shift workers are always out in force.
They work behind the scenes until the rest of us take over the reins as the sun comes up.
But while working nights may not be good for your social life or family relationships, a new report has claimed that it can also cause health concerns if continued for a long period of time.
Researchers at the University of Pennsylvania in the US found that sleep loss may be responsible for injury to and loss of neurons, which are essential for alertness and optimal intellect.
"In general, we've always assumed full recovery of cognition following short and long-term sleep loss," said researcher Dr Sigrid Veasey in an interview.
"But some of the research in humans has shown that attention span and several other aspects of cognition may not normalise even with three days of recovery sleep, raising the question of lasting injury in the brain."
We spoke to three people, who have experience of working through the night, to see what their job entails, how they feel it affects their life and what they do to keep fit and healthy.
The Disc Jockey
Radio DJ Mike O'Brien (33) is married to Helen and has two sons -- Darragh (6) and Joe (2). He does the overnight shift on Classic Hits 4fm five nights a week and has been working the airwaves during the small hours for the past three years.
He says he doesn't feel unreasonably tired but does try to ensure he gets enough rest, nutrition and exercise when he is off work to compensate for the unsocial hours.
"I have always had some sort of a job in radio, since I started on pirate stations like Freedom 92FM back in 2001, and have been doing the nightshift on Classic Hits for three years now.
"My job as the overnight presenter includes preparing features for the show, preparing the playlist for the week ahead and any other odd production bits and pieces that need doing around the station.
"Despite the hours, I do enjoy the work immensely. My working day starts around midnight when I get to the station -- I start by checking my emails and then get on with preparing the evening's show.
"My colleague Niall Boylan finishes at 1am and that's when I take over the reins of the station.
"My show is broadcast five days a week from 1am to 4am and our listenership has grown in each survey we have done for the past three years.
"I've worked hard trying to grow my audience, so I'm proud of both the work I do and being part of such a vibrant station.
"I have always been a bit of a night owl and over the years have also had a job as a barman in Harry Byrnes Pub in Clontarf, so working nights has never really been an issue for me.
"In fact, I quite enjoy the quiet roads and the non-existent traffic jams going to work.
"But working nights definitely affects your social life as you have to plan well in advance.
"I enjoy a pint with a few of the lads in the local GAA club at Raheny whenever I can and play junior hurling down there, so that helps to keep me half fit.
"Saturdays and Sunday afternoons is always family time when myself and my wife Helen spend time with our two boys. Most weekends we would head over to St Anne's Park to let them have a bit of a run around.
"Although people usually think nightshifts can be exhausting, I don't feel tired all of the time and would say I'm no more tired than anyone else who works shifts.
"But I really believe that trying to eat fresh and healthy food helps your body adjust to the abnormal hours.
"As regards missing out on stuff because of my work, I don't feel that I have missed many important occasions over the years -- because if it's important enough I will be there.
"I don't know if working nights is bad for your health, but the hardest part of working these hours is the broken sleep.
"My wife works full-time as well, so I have the boys ready for school before I can get a few hours in bed. There's a bit of juggling involved, but it works for us."
Roz O'Neill is 40 years old and lives in north Co Dublin. She works nights as an aviation firefighter and paramedic at Dublin airport and has been doing the job for so long that she can see an impact on her well-being. But she feels the key to staying healthy is to eat well and get exercise whenever possible.
"My job involves responding to fire and medical emergencies on aircraft and buildings and I work 12-hour shifts which I have been doing for the past 15 years.
"There are some benefits to working nights, which include being able to get personal business done during normal office hours, but having a social life is difficult as we work weekends, bank holidays and Christmas so we do miss out on events and family gatherings.
"I also feel that working nights is bad for your health -- sleep patterns are disrupted especially with a quick turnaround roster.
"I feel tired constantly and notice an improvement in my general well-being when I am off work and have a proper sleep pattern.
"Eating habits suffer also, especially during the night, you may or may not even want to eat and this is unnatural. So I don't think this see-saw effect is healthy long term.
"For someone thinking of starting night work, I would advise considering the effect it will have on your personal daily life.
"While night work suits some people, studies show sleep deprivation has a huge impact on life expectancy and health long-term.
"So I would advise people to ensure they get adequate sleep and eat as healthily as possible.
"Also, exercise plays an important role in general health. While this is probably the last thing you want to do when you wake up of an afternoon, you need to do as much as you can."
Twenty-three-year-old Naomi O'Shea lives in Dunboyne in Co Meath with her parents, her brother Adam and sister Rachel.
She works as a bartender in Sin É on Ormond Quay in Dublin City where her partner Kev is the events manager.
She works until the early hours of the morning and says while her job is hard work, it's also great fun.
"I drive in and out of the city each night for work, usually starting around 10pm and finishing about 4am.
"We serve until 2.30am. However, it's the clean-up and chit-chatting that keeps us there longer. But I prefer having a chilled-out clean-up and a laugh with my colleagues as it makes the late night a bit easier to bear.
"The good thing about working nights is that I've most days free, can see friends and family and keep up with chores and shopping.
"However, the downside is I normally sleep until at least midday after a full night shift.
"Also, it's very tiring as its non-stop physical work, I'm on my feet and up and down the stairs for at least six hours in one night -- or longer if I start earlier.
"There's also the psychological side to bar work that people forget about -- the stress of getting past people and pardoning yourself each time and getting many dirty looks.
"I thoroughly believe that people in this industry have the patience of saints dealing with some customers.
"But while you get extremely arrogant people with no manners, you also get others who are very kind and will help you get through crowds, or pass empty glasses from a table you can't reach.
"Another upside is that I get to see a lot of my friends quite regularly in work, so that automatically makes my night better and means it's quite easy to have a social life and see my family.
"When I'm off work, there is enough time to meet friends for a coffee, take the dogs for a walk, or, on a night off, head to the cinema with Kev -- I don't let my job stop me from living a normal life.
"So I don't believe that working nights is bad for my health, because I still get at least six hours sleep the night after, and I don't drink while I'm working or on my break or even when I'm finished.
"The only unhealthy thing is if I get hungry, I end up munching on a bag of crisps -- other than that I live a completely normal life, just a few hours later than others do.
"The best advice I could give someone working nights, whether in bars, hospitals or security, is to not let it take over -- you can have and live a normal life seeing friends, going out or having a relationship.
"But you need to be prepared to miss celebrations such as New Year's Eve, St Patrick's Day and birthdays.
"Keep in mind, though, there are much worse jobs out there and if you're the right person for working in a bar, you can have a lot of fun."