为什么一拿起书就犯困？

许多人都有睡前读书的习惯，不只是因为他们是书虫，还因为读书的助眠功效实在太赞了。你可知道，为什么自己一看书就犯困？

许多人都有睡前读书的习惯，不只是因为他们是书虫，还因为读书的助眠功效实在太赞了。你可曾好奇过，为什么自己一看书就犯困呢？     You’ve finally tucked yourself into bed and cracked open the detective novel you’ve been waiting all day to get back to. Three pages later, you’re fighting a losing battle against two suddenly very heavy eyelids.