||normal. Need a full 8h of sleep
rs121912617, also known as Pro384Arg or P384R, is a SNP in the basic helix-loop-helix family, member e41 BHLHE41 gene. Note that some publications and OMIM refer to this as Pro385 (rather than 384).
Individuals heterozygous for rs121912617 are known as Familial Natural Short Sleepers (FNSS), and they sleep 6–6.5 hours per night (∼2 hours less than controls) on average, without reporting any sense of sleep deprivation.[PMID 19679812] This is classified as a sleep disorder, although it does not appear to have any known negative medical consequence.
The correlation between P384R and FNSS was first reported in 2009. In 2014, an independent group studying a (relatively small) group of people also saw the correlation between P384 and FNSS, while also finding another similiar variant in the BHLHE41 gene, Y362H (c.1084C>T; also known as Tyr362His). The Y362H variant does not have a dbSNP SNP designation at this time. [PMID 25083013]
Research published in 2018 suggests that in human short sleepers, this variant weakens the DEC2 protein's ability to suppress the MyoD1 protein, which in turn leads to more orexin production, causing short sleepers to stay awake longer.[PMID 29531056];news