On the subject of Hanoian winters

If anyone tells you that winters in Hanoi are warm, they are lying. Granted, 15° hardly compare to the ice and snow the northern hemisphere experiences towards the end of the year, but in Hanoi, 15° outdoors means 15° indoors. There is no warmth ever, anywhere. Houses have poor insulation, heaters are non-existent. Going to your favourite café to warm up over a cup of coffee? Forget it, that coffee may be hot but the rooms are chilly. People take to wearing their coats 24 hours. The entire city is fitted out with gloves and earmuffs. Laundry takes days to dry. My boss advised me to wear socks to bed, and I certainly do. I keep a blanket wrapped around me at all times. I own house slippers that look like they could belong to Al Bundy. Along with the cold comes a distinct lack of sun - in the four weeks that I have been living here, we have not had a single day of sunshine. The sky remains grey from sunrise till sundown. I wonder what the symptoms of Vitamin D deficiency are...