Something very strange happens to me during this neither-one-thing-nor-the-other hinterland between Christmas and New Year. It usually starts on Christmas Day. Despite my resolve every year to wear something nice, the rest of my family are invariably forced to eat their turkey across the table from the unedifying sight of me in pyjamas pre-dating my O-levels or, if I'm really making an effort, some kind of M&S loungewear involving fleece and/or elastic.

I'm now unlikely to put on anything that could be described as outerwear until New Year's Eve – which is secretly one reason I generally try to wriggle out of going out, so appalling is the thought of reintroducing my limbs to non-stretch fabrics.

Spending the festive period at one's family home is a big part of the problem. No matter how many years I clock up, I remain the youngest of the brood and so escape the condemnation I deserve when I refuse to let anyone else hold the remote or stop me from eating an entire giant Toblerone before 11am. Ditto dressing like I'm attending a tweens' pyjama party 24/7.

That's my excuse, anyway. I don't know what everybody else's is, since it looks as if my obsession with cosiness has captured the nation this winter.

Collective oohs and aahs over colleagues' purchases have not been elicited by killer heels or bodycon dresses recently, but by fleecey Uniqlo pyjamas and Gap's cable-knit booties. Peacocks recently announced that sales of its £6 flannel PJs are up 50 per cent (I can take some credit – I had two bargain pairs in Westwood-esque tartan stockpiled by November). And I'm not sure whether the infamous "slanket" qualifies as clothing or soft furnishing, but the fact that somebody is making money out of adding sleeves to a blanket demonstrates the intensity of our fixation with all things soft and snuggly.

Of course, menswear tends to be more comfortable by definition, so presumably the lure of loungewear is slightly less tantalising for guys, but even their clothes have taken a similar turn this season, with lots of chunky knits and traditional Fair Isle patterns. Still, I'd be interested to know how many blokes plumped for flannelette over frou-frou undies as their girlfriend's Christmas gift last week.

Initially I thought this was rather sweet, as trends go, but the more I witness it, the more disturbing the idea of grown-ups donning what are essentially kids' clothes becomes. Adult-sized fleece all-in-ones (surprisingly easy to come by) are where this tips into specialist-interest territory. It's almost enough to make me go and put on some proper clothes. Tomorrow, perhaps.