How are sleep patterns typically affected by age?
a. Older adults typically sleep very soundly for longer periods through the night than they did when they were younger.
b. Older adults commonly have longer periods of REM sleep, or dream sleep.
c. Older adults must nap more during the day in order to accumulate the sleep they need.
d. Older adults tend to become "night people" by going to bed later at night and getting up later in the morning