You'll be surprised at the answer
I've always been fascinated with Bumblebees. These chubby little creatures, it seems, can pack more activity into one day than I can muster for an entire year.
Just around twilight last evening - I wasn't sure if it was my imagination or a trick of nature - many our resident garden bumblebees (Bombus hortorum) appeared to be mildly sedated, as if they were finished with their work day and needed a nap before heading back home.
Searching around a bit on the internet, I found this short little article, Bumblebees Sleeping in Flowers, which matches perfectly what I've observed in my own garden with regards to the Garden Bumblebee . And while you're at it, enjoy my collection of bumblebee activity.