NAP TIME! Why is it we nap?
ricca_m at pavo.concordia.ca
Tue Jun 21 09:39:00 EST 1994
NAP TIME: WHY IS IT WE NAP?
I have often wondered what is the significance of napping
after the lunch time meal. Did it really have an evolutionary
origin and survival impact? Let's consider some information.
It is common practice for somu wrestlers to sleep immediately
after a meal because this allows for more of the calories to be
laid down as fat. With respect to survival of a species, storing
fat is good since it provides some guarantee that if there is a
dearth of food tomorrow the body can extract some calories from the
deposited lipid and glycogen stores (before it consumes vital
protein tissue from skeletal muscles and organs) to still keep it
functioning and alive. Therefore I think that the mid-afternoon nap
is one means by which the body has come to store a larger
proportion of the ingested calories as fat.
Most people are familiar with the lethargic feeling that
accompanies a large meal. Often if they lie down they will nap.
However, if they keep moving around with some particular activity
they will not feel the need to nap. Does activity offset the nap?
I am familiar that napping may be a result of the extra blood
flow that is diverted to the viscera--specifically the stomach and
intestines--so to absorb the nutrients in the gut. In other words,
the sluggishness is caused by the decreased blood flow to the
brain. But if this is so, then this same effect would be responsible
for the sleepiness we experience prior to bed time--but ain't
so. Napping might be a consequence of our circadian
rhythms known as BRAC (basic rest-activity cycle) which are
responsible for the different levels of alertness during the day.
However, sleep onset most likely results from the activity in the
reticular formation that regulate norepinephrine and serotonin
Perhaps the sluggishness we feel after a meal, especially at
lunch time, is compounded by the increased blood flow to the
viscera and the coinciding of BRAC. Therefore, whether we eat or
not at lunch time we would still experience a sluggishness due to
BRAC. Yet, maybe it may be argued that if one doesn't eat around
noon there may be a drop in blood glucose which will incur fatigue.
On the other hand, if the lethargy is produced by the decrease
cerebral blood supply, then a similar effect should be noticed when
we are engaged in exercise. That is, since 85% of the blood flow is
diverted to the working muscles during aerobic exercise shouldn't
this diversion reduced blood flow to the brain, too?
Anyhow, these are some of the things I have considered. I am
not concerned with being right. I am just trying to derive and
explanation for this phenomena by amalgamating the different pieces
of information I know. So, if anyone has any insight to this,
please jump in. Let's get the most--presently--plausible
explanation for this napping business.
Enjoy the rest of your stay on Earth,
email: ricca_m at pavo.concordia.ca
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