What nobody ever told us about boredom. /
Facts about boredom that nobody ever told us.
Firstly, the fact thet we do wrong things. Also, we are more likely to lose our concentration and then make (more) mistakes. All of that often happens when we are under the effect of into the prolonged boredom/out of boredom. (or perhaps: under the influence of boredom.)
Something/someone is boring (adj.)
Boredom is a noun, meaning a tedious/monotonous state one is in.