This is exactly what I started writing before I saw your post. :) (Does that make this a discouraged “me too” post…?) TFA correlates _more_ sleep with increas

This is exactly what I started writing before I saw your post. :) (Does that make this a discouraged “me too” post…?) TFA correlates _more_ sleep with increased mortality, but barely speculates on cause, and lumps too much, and not enough sleep together in discussion. With respect to the question of how more sleep might be bad, the article states: "[...]one can speculate that these folk, who have lower moods and more worry, might struggle to get to sleep or to get up promptly in the morning. Lower scores on extraversion were indirectly linked with increased risk of death, thanks to an association with greater daytime feelings of fatigue (perhaps extraverts’ greater daytime activity levels makes it easier for them to get a satisfying night’s sleep, but this is speculation)." Anecdotally, I think sleep deprivation increases my neuroticsism and decreases my extroversion, so I feel like positive feedback could exist. This makes it harder to do the things that seem to me to improve sleep and mood, like aerobic exercise, exposing oneself to natural light cycles, and other people, and keeping a consistent personal routine. I feel like I have spent periods in a meta-stable state of insomnia after pushing myself too hard because of crunch time, international travel, etc. I suspect that "excess" sleep may be correlated with chronic health problems like mood disorders (like depression), or auto-immune disorder. These problems are known to be suggestively correlated with each other, and also with sleep problems. This stuff seems complicated enough to be pretty hard to figure out, and I think you are right to be skeptical about the direction of causality. Pretty sure not sleeping enough is still bad though. (edit: flow/clarity)