http://gigazine.net/news/20130602-technology-before-bed-linked-with-stress/

http://gendai.ismedia.jp/articles/-/35789

http://article.okinawatimes.co.jp/article/2013-06-02_49969

http://www.47news.jp/CN/201306/CN2013060301001406.html http://blog.livedoor.jp/schulze/archives/52022764.html

http://www3.nhk.or.jp/news/html/20130603/k10015018111000.html

http://book.asahi.com/reviews/column/2013053100002.html