URL: https://4.bp.blogspot.com/-Z39-qi7e-4s/XmbnGtKcmrI/AAAAAAAAcl8/5OTr52LcSF8ynYnj5e36eMS7MQyqQO_2gCKgBGAsYHg/s1600/1280px-Sleep_Hypnogram.svg.png
URL2: https://www.nagahitoyuki.com/2020/03/when-i-cant-sleep-i-would-like-to-endure-only-3-hours-non-rem-sleep-at-the-very-deep-sleep-stage.html
