I can't say for everyone else whether boredom makes them sleepy but I know it does for me.
Even with everything we have today I sometimes still get very bored at home and when I do get bored I go to sleep early.
I work from home blogging and sometimes during a blog post that I'm writing I will start to nod off because I get bored of sitting there typing.
But on the bright side after I wake up I feel more refreshed and can think more straight about what I'm writing in the blog post.
If I did that at an office I would be fired but since I work from home and don't need to write a blog post everyday I'm fine to just nod off or walk outside away from the computer if I want too.
On nice days I take my laptop outside to my patio table and blog that way as I feel much better outside due to the refreshing air and nice natural sunlight.