Abantu abalala ngaphantsi kweeyure ezingama-6 ngosuku okanye ngaphezu kwe-9 baya kuba nzima
Ubuthongo obuhle kakhulu kumntu omdala ziiyure ezisixhenxe ukuya kwezi-ezisibhozo, ngokutsho kwesifundo esitsha esithunywe nguRhulumente wase-US. Esi sifundo ngexesha elifanayo lidibanisa ukucinga ngokubhema ngobuthongo obaneleyo, kunye nomsebenzi obuthathaka kakhulu - ngokusetyenziswa kotywala. Iingcali zenzululwazi ziye zazimisela ukuba ukugqithisa kunye nezinye iingxaki zempilo zivame ukubonakala kulabo abangenalo ubuthongo obuhle. Zonke iziphumo zibonisa ukuba impilo inobungozi kokulala okugqithiseleyo kwaye imfutshane kakhulu, abaphandi bayaphawula. Izigqibo zenzululwazi zaseYunivesithi yaseColorado zisekelwe kuphando lwabantu abangama-87,000 baseMelika ukusuka ngo-2004 ukuya ku-2006. Ngethuba lophando, ezinye izinto, ezinjengokudandatheka, ezinokubangela ukuba ukutya ngokutya, ukutshaya, ukungazinzi kunye nezinye iingxaki aziqwalaselwe.