The pre-Christmas week can be brutal, too. If you're freelance and single, you can be damn sure employers/clients will ask you to finish every single project for 2016 (however tentative) by end of play today, so they can take three weeks off with their families.
Lovelorn, bleary-eyed, you get up at 5am every morning and reach for the black coffee.
No wonder a young woman named Bridget gained thousands of online fans this week after someone claiming to be her brother-in-law began posting her "very single" Christmas cards online.
As the last unmarried of five siblings, Bridget began in 2010 to send Christmas cards to friends making light of her single status. In the cards she sends up traditional images of the sad singleton alone at Christmas, from an alcohol-fuelled tea party to a romantic boat trip with a male mannequin.
The 2012 version saw Bridget get creative with a table full of multiple versions of herself, and a message signed by "Bridget, Bridget, Bridget, Bridget and Bridget".
There's something about the psychic pull of a family Christmas that makes sane adults agree to be cooped up together for days, surrounded by tinsel and turkey curry buffet. My sisters and I often sit on the sofa, like cuckoos waiting to be fed.
Two of us didn't feel the need to marry; my younger sister has a girlfriend (the nicest addition to our family). The rest of the year, this makes us slightly exotic. But come Christmas it's hard work.
Meanwhile, a UK study by family law firm Vardags reveals one in six Britons is dreading Christmas because they will be with their partner so much.
One in four thinks the pressure and cost of the holiday period will strain their relationship with their partner.
"Finances cause stress in relationships at the best of times and Christmas is like a pressure cooker for this," says the firm's president, Ayesha Vardag. "Add the fact that the whole shebang is so expensive, and you have the recipe for a break-up."
But there is hope for the uncoupled-up. Let's face it, we have nothing to lose. You just need to follow a few modest guidelines.
1. Romance
The good news is there are lots of rackety singles around, dying for a pre-Christmas hook-up. And the bad? Tinder is raining frogs. (I always find it helpful to remember that so-called romantic Christmases of the past were rarely that.)
2. Benders
Oh alcohol, you false friend. Partly, it's the strain of constant socialising. Dogged by tiredness, we blurt out tactless comments, knock over glasses, insult the boss. The next day we fear we'll have to leave town/lose our friends/resign ourselves to never being respected professionally again. The solution is to butch it out at work or go to bed. Relief will come at 7pm, when you decide to do it all over again.
3. Beware the raised dance floor
It's all very well throwing shapes with the cool people at the office party, but call it intoxication, call it wearing new boots on a small stage, I once tipped completely over the edge.
4. Presents
Say no to cat ephemera. Yes, many of us singletons have cats, but can we just stress how much we loathe tea towels and notelets and ironing-board covers adorned with cute felines?
5. Siblings
My sisters and I operate a cunning rota, which is the only way for 40+ grown-ups to pull off the Christmas trial without murdering each other. We arrive home at staggered intervals, so no one has to be relentlessly cheerful all the time. Sometimes we're not even in the house at the same time.
6. Keep busy
Catch the last train. When you arrive there's time for Baileys and bed. Next day is an orgy of present unwrapping.
7. Take a laptop
The modern family home is a shrine to TVs and DVD players. But let's face it, no one's going to let you watch anything you want. So your laptop is your new boyfriend. Make sure you download European arthouse films and lots of cheesy rom-coms - everything from The Holiday to It's A Wonderful Life.
8. Social media
Go gently. Twitter, Facebook and especially Instagram may break your heart with images of blissed-out families. Texting is your friend - your last contact with your single tribe.
9. Fashion
If anyone asks about your "Christmas outfit", laugh hollowly. No one needs another ill-fitting cocktail dress or novelty onesie.
10. Embrace the single bedroom
There's something surreal about waking up in your old teenage bedroom. You lie in the nun-like single bed, surrounded by A-level certificates and posters of Pre-Raphaelite heroines (catnip for depressed teenage girls) and think: "Where is my glamorous life?"
11. Waif and stray parties
Even the smug marrieds enjoy the company of floating singles (gay and straight) on Christmas Day. Ask around for a friendly open-house. Bring fizz and artisan cheeses and don't make a fuss about taking part in karaoke Singstar.
12. Hold your nerve
Meltdown point is Boxing Day at 4pm (no meal pending, dreadful telly). Just be nice. Incredibly, suspiciously nice. Always floors them. Remember you're making a memory. And, humbling thought, not everyone has parents they can go back to any more. The cuckoo years are on loan. Memo to self: don't ruffle too many feathers this year.
13. Hit the office
Colleagues with kids will love you if you cover their post-Christmas shift. The working day is fairly short. And afterwards you can rejoin your tribe at the (refreshingly empty) cocktail bar.
14. It's okay to cancel Christmas. Seriously.
Put the money towards a cheap flight in January (when the school holidays are over and prices drop). Darling, if you're not part of the 2.2 nuclear family, you need somewhere fabulous to go.
