Because of the recent hot summer weather, it seems like I'm using twice as more physical strengh in my daily life than usual. I guess the main reason for this is because I ride my bike to work everyday and use most of my physical strengh. So at night, I'm so tired and sleepy. Last night, I went to sleep a little after 9PM but got up at my usual time. But I still feel my body can rest. Ah-, maybe I'm already tired out from the summer heat??