Margaret Talbot has a long article about boredom research in the New Yorker.
Fundamentally, boredom is, as Tolstoy defined it, “a desire for desires.” The psychoanalyst Adam Phillips, describing the feeling that sometimes drops over children like a scratchy blanket, elaborated on this notion: boredom is “that state of suspended animation in which things are started and nothing begins, the mood of diffuse restlessness which contains that most absurd and paradoxical wish, the wish for a desire.” In a new book, “Out of My Skull: The Psychology of Boredom,” James Danckert, a neuroscientist, and John D. Eastwood, a psychologist, nicely describe it as a cognitive state that has something in common with tip-of-the-tongue syndrome—a sensation that something is missing, though we can’t quite say what.
In Talbot's account researchers are divided between those who think boredom is a universal human thing, in fact shared by many animals, and those who view it as a particularly modern condition. My reading of history and anthropology is that people have always suffered from boredom, and to the extent that they were less bored than we are it was because they were scrabbling to survive. I do find it interesting that the explosion of amusements – the internet, 500 televisions channels – has not reduced how much boredom people report feeling. I suppose this is because most of what we consume is so unfulfilling as to leave us thirsting
And this for all the educators in the audience:
A 2016 paper found that, for most Americans, the activity associated with the highest rates of boredom was studying. (The least: sports or exercise.) Research conducted by Sandi Mann and Andrew Robinson in England concluded that among the most boring educational experiences were computer sessions, while the least were sturdy, old-fashioned group discussions in the context of a lecture. Mann, in “The Science of Boredom,” makes worthwhile observations about two tactics that help people feel less bored while studying: listening to music and doodling. . . . The boredom trough of school may also be a matter of age: studies that have looked at boredom over the life span have found that, for most people, it peaks in their late teens, then begins to drop.
Personally I understand boredom in terms of a barrier that has to be climbed to get to something I would enjoy doing. For example, I might really enjoy a backpacking trip with my brother or my sons, but that would involved me in a mountain of planning and organizational effort that I don't feel like getting into right now. Even something simple like a family boardgame involves getting enough of my children to agree to 1) play a game, and 2) agree on what game to play. Working on one of my writing projects requires a level of effort that is often insurmountable but sometimes, for whatever reason, trivial and easily brushed aside.
This, I think, is the connection between boredom and mild or moderate depression: depressed people find even small obstacles between them and pleasure impossible to overcome, so they spend more time doing nothing. I think this also explains teenage boredom: teenagers are restless but lack the organizational and financial resources to arrange to do the things that might distract or fulfill them.