A．its effect may linger for almost 10 hours.
B．it disturbs the way people feel in daytime.
C．it accelerates heartbeat and respiration.
D．they may want to take a catnap.

A．Napping for 2 hours is better than for 40 minutes.
B．It does not revive you if the nap lasts too long.
C．You should never take a nap after lunch.
D．The longer you sleep, the better you will feel.

A．Create a comfortable sleeping environment.
B．Prioritize sleep if you are haunted by sleeplessness.
C．Climb into bed early and lie awake to relax.
D．Show perseverance and prepare for a long battle.