For those of us in the business of selling clothes, January is what we tend to think of as “essentials season”. After the surfeit of holiday gifts and sale impulse-buys, you’re likely to have amassed more than a few new additions to your wardrobe (several of which might well be earmarked for a speedy exchange). It follows, then, that January should be about a clear-eyed appraisal of what you don’t have, and what you need to get you through what’s likely the bleakest month of the year.

We’ll get right to it: you need a pair of pyjamas.

Not the jaunty, reindeer-nose-embellished kind that you wore on Christmas Day. Not the holey T-shirt and sweatpants that you’ll slide into after a particularly hedonistic night before. We’re talking about a well-cut, grown-up PJ set that you wouldn’t be ashamed to pad around the house in on a chilly Sunday in January. After all, it is the official month of nesting.

For inspiration, it makes sense to look towards the Swedish, who have built an entire lifestyle aesthetic around the concept of staying in when it’s cold. Consider, then, Mr Ingmar Bergman’s highly influential (and controversial) mini-series Scenes From A Marriage, which celebrates its 50th anniversary this year. The series, which follows the uncomfortably strained relationship between a pair of intellectuals (played by Mr Erland Josephson and Ms Liv Ullman), was frank in its portrayal of abortions, affairs and divorces. (Should we offer spoiler alerts for 50-year-old TV shows?)

In its style, too, the show still feels bracingly modern. Josephson has often been overlooked as a style icon from that period, but his wardrobe is worth revisiting: his rumpled, unstudied approach to getting dressed could have been pulled directly from the rails of Massimo Alba or Loro Piana. Throughout the series, he has a laid-back but grown-up aesthetic that avoids the clichés of early 1970s style. It is mercifully free from giant shirt collars.

But it’s his pyjamas that warrant a closer look. The shirt-and-trousers combination that Josephson favours throughout the series (in a variety of colours and patterns) have fallen out of favour in recent years, but they shouldn’t have. One: they’re warming when the weather’s cold. Two: they’re less likely to stretch or rip than jersey. Three: their roomier shape means you can wear them in front of the family without worrying about revealing the entire contents of your… war cabinet. Four: if a workman comes to the door, or you need to pop out to collect your post, you won’t feel half as exposed.

Avoid anything that could be described as “jaunty”, and look instead for subtle, classic detailing – the white piping on Josephson’s shirt lends it definition and precision. Cotton and linen are, generally, a better option than flannel, which is likely to make you feel sweaty.

As for brands, you could do a lot worse than by leaning into the Scandinavian direction of the show; the Danish brand TEKLA is an expert at smartly cut yet satisfyingly minimal pyjama sets, made from organic cotton in a host of pleasing colours. Elsewhere, the Savile Row tailor Anderson & Sheppard’s pyjamas are made from a blend of cotton and cashmere, which really takes the joy of staying in to almost Marie Antoinette-levels of pampering.

Lastly: it is, apparently, a good idea to machine-wash your new pyjamas before you first wear them. Not only will it make them less stiff, but it will, apparently, make them less likely to absorb smells. Even Scenes From A Marriage’s most tense scenes didn’t have the added strain of early-morning armpit fog.