Typically when we’re reading, we do it in a comfortable position – sitting or lying down – in a quiet place, and often at the end of the day or after more energetic activities, all of which contributes to a state of relaxation and sleepiness. Also, an absorbing text will take your focus away from the outside world and from anxieties that might otherwise keep us alert, such as worries about tomorrow’s exam or dentist appointment. Alternatively, if you find what you’re reading boring, the effort to keep going can be tiring, in which case you’ll likely begin to daydream, which can also bring sleep closer.