For the fast-expanding crowd of westerners living in the Russian capital, the warm weather has been welcome. But for Russians, it has led to an attack of collective angst.

Muscovites have been shaking their heads and muttering darkly that nothing good can come of winter's failure to arrive, while Russian television news has made much of warnings that the lack of snow, coupled with the short, dark days, could lead to an outbreak of national depression. Snow, it seems, reflects what little sunlight there is, helping to trigger the brain to produce more mood-enhancing chemicals.