Thais seem to have a completely different sense of temperature. farangs would say it's hot today, it's up to 28-30 degrees out in the sun now. but nighttime temperatures are down to around 15-17, so ALL my colleagues have caught a cold, sneeze and shiver all the time, and sport heavy jackets and it's much worse up in the mountains. so, my logic would say many of those who drink do so to keep themselves warm in the "cold" season