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NAP TIME! Why is it we nap?

MUCCIACCIARO, RICCARDO ricca_m at pavo.concordia.ca
Tue Jun 21 09:39:00 EST 1994


     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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