system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we often feel tired after low-energy activities such as sitting on a plane?
gpt
Well, that particular example inflicts quite a bit of stress, both emotional (lines and such, even assuming you aren't afraid of heights), and biological (altitude change, uncomfortable seats and restricted ability to move, persistent noise, and the like). Driving is another good example, again emotional stresses (if you're not occasionally getting mad while driving, you're probably not paying attention), and physical (restrained seat with limited ability to shift positions, sustained effort and concentration).