One thing I love about Thailand except for beautiful weather and lovely people is the simple way of life. Thais eat when they are hungry. They sleep when they are tired. It doesn't matter what time it is or where they are. If you walk into a shopping centre like MBK (not Siam Paragon...) you see people sit on the floor with their legs crossed having a bowl of noodles. In the same shop someone could be sitting behind the counter with his/hers head firmly on the desk next to the till, sleeping in between customers. 
There are so many people working in every shop so I guess if a couple of them fancy a kip for a while there's no problem.