Nightwear before Christmas poses new fashion dilemma...

One of the best places for spotting curious new trends is the friends' news feed page on Facebook.

- with Mike Hill

On Christmas Eve-when there are, admittedly, more festive things to do than scroll through social media - a pattern started to emerge as the clock ticked towards midnight.

When everyone should have been wrapping presents, sipping Baileys and watching Home Alone, a stream of photos started to appear of families posing together in their pyjamas.

And to add to this mystery of seasonal symmetry, in each picture they are wearing matching outfits like football supporters on cup final day.