"Sweet dreams are made of this," sang Annie Lennox during her stint
in the Eurythmics in the 1980s. But you might notice that Lennox is
suitably vague about what exactly "this" is. And really, no one knows
what sweet dreams are made of, why we have them or even what we're
doing sleeping our life away anyway.



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Why do babies need so much sleep? Another mystery!
Can you believe that? Every night we carve out a few hours of shut-
eye, and scientists don't even know why! They do know that it's
extremely damaging if a person doesn't get enough sleep, and it's
possible that sleep once served some sort of evolutionary benefit.
Sleep would be an extremely beneficial distraction if early man had
wanted to take a midnight stroll at the time when saber-tooth tigers
were on the prowl [source: BBC]. On the other hand, it's not a
particularly advantageous trait to carry forward in this age of
electricity as the process takes up a lot of time (about a third of
our life) and renders the dreamer defenseless against predators
[source: Eagleman].


There are a few theories as to why we need so much sleep. One idea is
that sleep is restorative to the body, giving it an opportunity to
rest. But if rest is the goal, why does our brain remain hard at
work? It's possible that while we sleep, the brain is practicing and
running problem-solving drills before completing actions in the real
world. There are several studies that show that learning can't take
place without sleep to reinforce the knowledge [source: Schaffer].


Some of these studies may have real implications for students. One
researcher claims that it would be better for students to review
information until they were tired, then slept, as opposed to pulling
an all-nighter [source: BBC]. Some schools have changed the time of
that first bell so that middle and high school students can get a
little more snooze time [source: Boyce, Brink].


So let's say these students actually go to sleep, as opposed to
engaging in more nefarious behaviors. What happens then? When the
dreaming state of REM sleep was discovered in 1951, it was described
as a "new continent in the brain" [source: Schaffer]. Though
scientists have tried to make inroads on this uncharted continent,
mysteries remain about its topography. Like sleep, dreaming may
represent some sort of personal gym time for the brain, with dreams
allowing a person to work out emotional issues and solidify thoughts
and memories.


Or, it's possible that life is but a dream, as the song "Row, Row,
Row Your Boat" taught us. When you're asleep, you're experiencing a
ton of visual stimuli that the brain is somehow processing. In an
awake state, there may be additional stimuli for different senses,
but the brain may be doing the same thing with them. If the brain
works just as hard sleeping as it is when we're awake, then maybe
life is a waking dream [source: Eagleman].


Let's row our boat over to the next page and investigate the
mysterious case of human memory.