Perhaps the most striking demonstration comes from a famous experiment in
which the ability to remember after a period of sleep was compared with the ability to
remember after an equal period of waking. Two subjects were tested for retention of
nonsense syllables after various periods of sleep and again after various periods of
normal, wakeful activity. The results of this study show that sleep was followed by much
higher retention than wakeful activity. This experiment has been repeated several times,
and the results are always about the same. Activity produces much more forgetting than
does sleep. Furthermore, after the second hour of sleep, retention hardly declines at all.