Absolutely perfect to sleep in (combined with matching simply Merino tank top!), Especially in the summer. I was eyeing these for a while, and the price was a bit too much for me to justify spending on my myself, but then my mom purchased as a gift for me. I'm so glad!
For the month I've owed my single pair, I have worn them daily. I sleep in them, wear them for a bit in the morning, then hand wash with lanolin soap (or soak with Eucalan) in the sink and hang to dry. They are ready for me by bedtime to repeat all over again. I'll need to get a second pair in order to have full 24/7 coverage ;)