I say this not because there's a potentially dangerous build-up of consumer debt - though there might be - but simply output almost always falls after Christmas. Real GDP has fallen in the first quarter of the year in every single year since 1974. And the falls are large, averaging 3.4 per cent in this time.
What's more, GDP doesn't always rise in the second quarter: in fact, if we take the standard definition of a recession as two consecutive quarters of falling GDP, we had a recession every year between 1998 and 2012.
If all this sounds odd, it is because economic figures are usually reported after official statisticians have smoothed away seasonal fluctuations. But these fluctuations are big. The usual pattern is for manufacturing output to rise very sharply in the autumn as firms gear up for Christmas sales, then to fall in December as firms shut for the holidays, but to recover only slightly in January and February. Output then booms in March before falling back, bottoming out in August before rising strongly.
In retailing, sales of course peak in December, bottom out in January and February before seeing another mini-peak in June and July.
So, if this year is anything like the last 40, we're heading for a sharp drop in GDP.
If you think this is just a funny statistical quirk, think again. It matters enormously in two ways.
First, because seasonal fluctuations can become something more severe. Yi Wen at the St Louis Fed has estimated that half of the ordinary business cycle fluctuations in GDP in the US between 1947 and 1996 originated in "merely" seasonal swings. Firms and customers who get out of the habit of spending in the new year don't always get back into the habit.
Secondly, this raises a question: if seasonal recessions happen so often without politicians and journalists noticing - let alone worrying - why do non-seasonal recessions cause so much fear?
It's not because 'ordinary' recessions are much bigger than seasonal ones. They're not. In 2008-09, real GDP fell by 6 per cent from peak to trough. That was the worst recession since the 1930s. But we saw bigger seasonal peak-trough falls in 1993 and 1995. And seasonal falls in GDP of more than four per cent have been common.
Instead, I suspect the biggest reason for the difference lies in a difference in the distribution of losses. In a seasonal recession, millions of people lose a little, whereas in a "proper" recession, a minority lose a lot as they become unemployed or see their businesses fold - and this spreads fear among countless others. There's a big difference between a student losing a Christmas job and a full-time worker losing their livelihood.
The pain of recessions lies not so much in the drop in national income, but rather in the way that pain is spread. This has a trivially obvious implication. That pain can be more evenly spread by better insurance - not just (or even) by the state, but by using insurance markets of the sort proposed by Robert Shiller.
Christmas should be a time for goodwill to all men. Such goodwill should consist, in part, in considering some basic changes that can help not only others but ourselves.
