Posted by F43 on March 15, 2009 at 13:59:52:In Reply to: Sleep Pressure posted by Dream_on on March 15, 2009 at 00:39:20:
Really interesting comments. I like Greene's notion of "sleep pressure." That overwhelming drowsy feeling is what stopped when my insomnia started. I feel like that is the elusive thing I'm chasing. And then when my sleep does resolve, there it is again, like it never went away in the first place.
Your observations are interesting. I wonder if there's something dietary going on? Or a conditioned expectation based on lifestyle or belief? I would be careful about concluding that this ability is genetically-based, based on seeing it in a few families of one ethnicity. Ethnicities are not the same thing as populations, for the purposes of genetic inheritance. Gene-linked traits are very complex and we don't understand how they're inherited or expressed (except for the rare, Mendelian kind). Even when we find certain alleles (gene variants) concentrated in higher proportions in certain populations, these populations are geographic. They only roughly map onto ethnicity. You can have several ethnicities with ancestors from the same region, all of whom have an allele at a higher proportion. So there is no simple one-to-one correspondence between an allele and an ethnicity. Also, the distribution of an allele varies within populations. So, if there is a concentration of an allele for sleep pressure in a population that maps onto this ethnicity, you can be sure that will be members of this ethnicity who didn't inherit this allele. Then you'd have to see if they, too, experienced the same sleep pressure or not.
See, you made such an interesting post and you got a lecture on population genetics in return. Hardly a fair exchange!
But really, I know what you mean. How do they do what they do? It is amazing to see people fall asleep like this.