So I went on a long detective quest researching, buying, and trying out different bulbs, until I finally hit jackpot. I'm not sure these light bulbs are meant for bedrooms, as they are very little and come in packs of 10. They may be meant for microwaves. But they worked.
They worked, that is, for a couple of months, until one day, they didn't. Their brightness dropped to much less than that of a candle. They were as bright as a firefly. We couldn't see anything.
I had many extra light bulbs in the box of 10, but the ceiling is rather high, so changing the light bulbs would involve getting the ladder from the garage. So several weeks passed without us doing anything about the lights. We used the night stand lamps instead, for over a month.
One day I bit the bullet, got the ladder, and replaced all four bulbs. Done!
But when I turned on the light switch, all of the four new light bulbs lit as much as a firefly.
I considered whether the light fixture may have gotten broken somehow and needed to be replaced, which would be a pain. Then I got an idea. I walked to the light switch and noticed there was a dimmer, and it was set very low. That was the problem. Probably one of us had inadvertently moved the dimmer while walking in the dark half asleep. The bulbs were perfectly fine.
Watch out. Those innocent-appearing, tiny dimmers look nice, but they're slimy, pesky little rascals.