Cell Phone Messages and Sleep Quality

Everyone loves to get a“goodnight”text. However, sending too many messages before ( 31 ) may affect your sleep quality.
In a recent ( 32 )， 83 college students responded to a(n) ( 33 ) survey about their sleep quality. They were asked to report the ( 34 ) number of text messages they send and ( 35 ) on any given day.Sure ( 36 ),researchers found that the more people text,the less sleep they get. Why? People often sleep too ( 37 ) to their phones. The ringing or buzzing (嗡嗡声) of late-night messages might ( 38 ) them out of their sleep. Worse still, people may feel pressured to respond ( 39 ) to messages even if they come in the middle of the night.
If you do not want to ( 40 ) your sleep, turn your phone off. If you don't give your phone a rest, you won't get any, either.

A.online
E.bedtime
I.far
B.knock
F.average
J.study
C.slowly
G.receive
K.immediately
D.enough
H.close
L.ruin