Depth of Sleep

　　I'm utilizing a PC application of Evernote every day. It's designed for the storage of documents, pictures, motion movies, and so on. I make it a point to scan every kind of paper, like documents concerning my job, receipts, postcards, letters, favorite articles from newspapers and magazines, even some books like my alumni address book. Once those papers are scanned and stored, you can pick up the documents which you want to see anytime and anywhere as long as you are connected to the net.
　　Anyway, a direct mail came to me from the Evernote company. It says, "Evernote is useful for keeping fit!" The company advised me to record my status of sleep using my smartphone.
　　Though I wondered how the smartphone can detect the status of my sleep, I tried to use one of the applications for smartphones which they recommended and I'll show you the result of it. The following two pictures show the sleep status on Nov. 25th and Dec. 1st. on which I had been in my office throughout the night.
　　It records when I went to bed and got up with the depth of my sleep. Actually it's when I was called to the ward that the level of the sleep became shallow. I was surprised at the speed I fell into deep sleep.