I think you should sleep. There is good reason for siesta - it recognises how we operate as human beings. It's normal to become tired in the middle of the day and this is recognised in many cultures, for example in Spain and Latin America, also Serbia where they take a nap. In Germany they call it the Mittagspause. In China, they do it as in other parts of Asia. I was in Japan recently, yes there too. Glucose after a meal inhibits production of orexins which maintain consciousness. Orexins play a role in a number of things including body weight, learning, sleep patterns and addictions. I had a friend at Uni from an island off India who seemed to regularly sleep in the middle of the day. He'd lock the door to his office, dim the lights and if anyone knocked pretend not to be there. He opened it for me because I knew what he was up to and that was a good time to catch him! If you do these sleeps, they need only be half an hour and you will have much more energy later for going to the opera or whatever takes your fancy.