In 2014, one in 16 Americans visited the ER for home injuries that resulted from, among other things, fumbling knives (the cause of at least 249,000 injuries), ladders (at least 105,000), and cookware (at least 22,000). One of the main causes of these accidents? A wandering mind, says Steve Casner, the author of Careful: A User’s Guide to Our Injury-Prone Minds. By one estimate, he notes, people daydream through nearly half their waking hours.
Psychologists have recently focused more intently on the tendency to think about something other than the task at hand. For one experiment, two Harvard researchers developed an iPhone app to analyze the relationship between daydreaming and happiness. The average person’s mind, the researchers found, wandered most frequently (about 65 percent of the time) during personal-grooming activities, and least often (10 percent of the time) during sex. Respondents’ minds tended to wander more when they felt upset rather than happy, and were more likely to wander toward pleasant topics than unpleasant ones. 
Drinking alcohol and daydreaming also seem to go hand in hand. In one study, participants who imbibed a moderate amount daydreamed roughly twice as much as those given a placebo drink.  And the younger we are, the more likely we may be to let our mind wander. People ages 18 to 25 report significantly more task-unrelated thoughts than do those ages 60 to 85.