It's January, the sun's high and you're back at the office. But there's a different vibe. Wearing shoes without socks is OK, playing the odd innings of office cricket is fine, and taking a lunch break away from the desk is perfectly reasonable.
There's a liveliness and a sense of fun, with a backing track from the office TV of cricket, golf or tennis, and even a hint of someone's Christmas-gifted aftershave permeating the aircon.
In short, it's the summer silly season and you're still making money. You're allowed to be relaxed - in fact, management, at some level, demands it.
The overworked professionals who skulked from their desks for the Christmas break have returned, refreshed and recharged. It's good for morale and good for productivity, according to workplace psychologist Amantha Imber.
"People cram so much work into December; there's a huge amount of exhaustion. But by the end of the break they're physically, emotionally and psychologically recharged," Imber says. "People come back much more innovative and creative and much better at problem solving."
And much sooner, it seems, particularly those in the corporate world. Fifteen years ago professionals took four weeks off in January. Now they are back at work as soon as doors open on January 7. But however brief and however punctuated by office emails, the holiday offers a chance to pause for thought.
Rene Johnston, director of Pacific Search Partners, says: "A lot of people use the Christmas break as a time of reflection on where they're going. They either come back refocused and hard at it, or they come back and make changes."
There's a flurry of inbox and desk clearing as people take the "in with the new" maxim to the office: those resolutions about diets and exercise are so much more tedious.
"There's a 'detox the office' perspective," says Charlotte Turner, who works in a predominantly female workplace for cosmetic distributor Trimex. "New year, new you, new organisation and approach. Everyone's madly decluttering."
It seems to happen with their work attire too. It's casual Friday every day. Some women take to revealing cleavages, armpits, knees and toes - sometimes all at once - while their male counterparts display calves, jowls and chests in a manner seen at no other time of year. Clothes become not only skimpier, but brighter.
Image consultant Bronwyn Fraser urges caution. Losing the jacket and wearing a lighter-weight suit are the only options for corporate men, she says, while women can wear a structured dress; "a power dress rather then a sundress".
But the majority who follow the "business casual" dress code do get to have some summer fun. Fraser says men can wear knee-length shorts with a shirt - not a T-shirt - and "a nice shoe, like a brogue without socks or deck shoes for the older guys. There are some nice casual shoes now - lace-ups and slip-ons."
Women can wear printed dresses and slingbacks or sandals - as long as they have a small heel or wedge.
Fraser says: "They're there to work and look the part. But it's also our summertime, it's school holidays, so they can relax the dress code a little."
Summertime and school holidays can alter perspectives - and send people scurrying for the sanctuary of the office in an unseemly, non-PC manner.
"If you've got kids, why on earth would you take January off?" says a solicitor who doesn't want his name published. He's a father of three much-loved boys aged under 10 who "do my head in" during the school holidays, so he prefers to keep working.
But he would work in January even if he wasn't a father. "That's when half the parents are off. The dynamics change for the better in the office, with even the temporary absence of any one colleague, let alone a quarter of them."