That’s the message of a recent study by Timothy Wilson and colleagues at the University of Virginia, reported in Science and written up in The Atlantic:

They report on 11 experiments. In most, they asked participants to put away any distractions and entertain themselves with their own thoughts for 6 to 15 minutes. Over the first six studies, 58 percent of participants rated the difficulty at or above the midpoint on a scale (“somewhat”), and 42 percent rated their enjoyment below the midpoint. In the seventh study, participants completed the task at home, and 32 percent admitted to cheating by using their phones, listening to music, or doing anything but just sitting there. (In the lab studies, one participant’s data was tossed because an experimenter had accidentally left a pen behind and the subject used it to write a to-do list. Another’s was tossed because an instruction sheet had been left behind and he used it to practice origami.)

Participants rated the task of entertaining themselves with their own thoughts as far less enjoyable and more conducive to mind-wandering than other mellow activities such as reading magazines or doing crossword puzzles.

Incidentally, participants in some studies were offered pleasant topics to think about, but that made no difference to results.

In the most, ahem, shocking study, subjects were wired up and given the chance to shock themselves during the thinking period if they desired. They’d all had a chance to try out the device to see how painful it was. And yet, even among those who said they would pay money not to feel the shock again, a quarter of the women and two thirds of the men gave themselves a zap when left with their own thoughts. (One outlier pressed the button 190 times in the 15 minutes.) Commenting on the sudden appeal of electricity coursing through one’s body, Wilson said, “I’m still just puzzled by that.” [Here's the study (paywall).]

And the cause?

Wilson favors the “scanner hypothesis”: Mammals have evolved to monitor their environments for dangers and opportunities, and so focusing completely internally for several minutes is unnatural. “It would be a little odd to see a chimpanzee posed like Rodin’s thinker for extended periods of time,” he said.

But that is a silly and instantly dismissible explanation. Many mammals are—and must be—capable of sitting still alone for long periods. Think of animals who stalk or rely on camouflage. They probably do not have (or miss having) an inner life, so their problems and the problems humans face when asked to sit still alone are mutually irrelevant.
Here is a more likely explanation, though it does not fit neatly into today’s pop science: When we are alone with ourselves, without distractions, much unfinished business, shelved not solved, comes to the surface. Often we would rather suffer anything, including pain, than deal with it.
This type of dread diminishes with the regular practice of solitude, as enjoined in many religious and philosophical traditions. For one thing, it eventually becomes possible to name one’s fears, angers, regrets, and remorses, and thus seek remedies or—if the troubles and conflicts are past all that, begin to let them go.
The traditions are correct. We must plan for solitude, just as we plan for fitness, so that it becomes comfortable with regular practice. Unfortunately, that is not the message that will be taken away from many reports on the findings. The following gee-whiz vid is likely more typical:
 

Denyse O’Leary is a Canadian journalist, author, and blogger.