People most frequently have bed-days:
A. when the weather is cold, rainy, snowy or unbearably hot,
B. when they're breaking in their new Egyptian-cotton bedsheets, or
C. when there's a "Law & Order" marathon on.
"Hey! Why weren't you at work yesterday?"
"I was laying in bed until 5 PM"
"What, were you sick?"
"Nope. Just day-dreaming about being in a coma."