According to the article, which statement about sleep debt is wrong? ( )
A.
(a) "Sleep debt" is a term created by the author and his colleagues.
B.
(b) The term implies that if you sleep less than you need, you tend to sleep during the daytime.
C.
(c) Sleep debt accumulates day by day and must be paid back.
D.
(d) In reality, lost sleep can be made up by sleeping all day long on weekends.