Typically, a human blinks 15 to 20 times per minute though some medical conditions may result in blinking at a rate noticeably outside the normal range. Two major functions of blinking include keeping the eyeballs moist and protecting the eyes from irritants, such as dust.
When an individual looks at a specific object for a long time, the rate of blinking decreases. Reading for an extended period can result in fatigue as the eyes gradually dry.
In 2012, research was published regarding the association between eye blinks and natural gaps in external stimuli, such as the spaces between sentences in written work. Analysis of brain activity during blinking episodes suggests that blinking plays a role in adjusting one's focus and in aiding concentration.