Is it permissible to sleep in a bed on Tisha B'Av?

Greetings,

There is a custom (not an obligation) to avoid sleeping in a bed on Tisha B'Av and instead to sleep on a mattress. Additionally, it is stated that one should minimize their comfort on the eve of Tisha B'Av; if someone usually sleeps with several pillows, they should sleep with only one pillow  [and those who typically sleep the entire year with one pillow should sleep without any pillow at all on Tisha B'Av]. However, weak individuals and pregnant women may sleep as usual (Shulchan Aruch and Rema, Orach Chaim 554:2, and the book Sha'arei Nechamah, page 258).

Blessings,

Hillel Meirs