A beholder's lair is made up of several chambers and...
The farthest chamber from the entrance is the beholder’s personal quarters, where the creature sleeps and studies any magic treasure it has accumulated. (Lords of Madness 50)
...but that's pretty much all it says. I know that, given their iconic status, far more than what's in the Dungeons and Dragons 3.5 accessory Lords of Madness (2005) has been written about beholders, especially in Advanced Dungeons and Dragons, Second Edition, so someone must've been tasked with writing about a beholder's sleeping habits and its choice of furnishings.
According to Dungeons and Dragons canon, do beholders sleep in beds? If so, what sort of beds do they prefer? Do beholders make use of other furniture?
Background: While designing a beholder's lair, I realized I had no idea what furnishings a beholder would require. (No, I didn't get very far. Thanks for asking.) Specifically, I didn't know if a beholder would have a bed or if it would need a bed. Further, I don't know to what degree a beholder relies on its at-will 325-lb.-capacity telekinesis to manage its belongings. I know I would a lot.
I've tagged this question both dungeons-and-dragons and dnd-3.5e because, while this is question concerns a Dungeons and Dragons 3.5 campaign, canonical information from other editions of Dungeons and Dragons is acceptable if information from that edition is unavailable.