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Have you ever thought why thinking makes us
? Researchers from Paris looked at why
effort makes us tired. When we think a lot, our brain releases a
. Too much of this changes the
. It tells the
that we must rest. People who spend a long
on a task are more
to feel tired. Resting helps the brain to return to normal. A
nap is good for us. A 20-
power nap can make us feel
refreshed.
