I haven’t slept by day for a long time. During these recent three days, however, I took a nap every afternoon at our quiet and warm apartment when I returned from work ahead of schedule. The sleep was short but sound, which refreshed me greatly. As it got warmer outdoors, the temperature indoors dropped that I couldn't doze off as before in our office at noon because it was draughty and cool. With the night beginning to shorten, it is necessary to have a short sleep in the daytime. When I woke up from such sleep, I often tended to misjudge the time for a moment thinking I had been oversleeping and late for work.