A hotel room generally feels way bigger than I need when traveling: I'm really just looking for somewhere to sleep. When I first read the Wikipedia page for capsule hotels, maybe 20y ago, this seemed like a very reasonable approach: lots of people could sleep in a small space, without the downsides of open hostels. I recently travelled to DC for work and found the U Street Capsule Hotel. Seemed worth trying!
For $82 I got a capsule for a Thursday night:
Some capsules were perpendicular to the hall, which seems a bit more awkward for getting in and out but would use the space more efficiently:
They were really very blue. Here's a photo from the inside:
Seems like they were designed by people who didn't know or didn't care that blue light is bad for sleep? You could turn off the light, though, so it wasn't that bad.
The thing that I wasn't expecting, however, was the minimal sound isolation. Before trying one of these I had assumed that the point of a capsule instead of bunk beds was noise isolation. While the other people in the room did a good job of being quiet, thin walls plus a window shade for a door did very little to keep out noise. Something more like a horizontal call booth (with active ventilation, and perhaps a failsafe to automatically open on power loss) would be a lot better.
The ventilation was also hard to control: it was somehow connected to the lights, where I accidentally turned the air off when turning the lights off and didn't realize until ~1am when it got pretty stuffy. This would probably get better with practice, but it could be a lot more intuitive.
Overall it was ok and I might do it again, especially if it were a lot cheaper than other options, but I liked it significantly less than I expected to.