== Sygdom ==
Mennesker kan blive søvnige som konsekvens af en [[infektion]].<ref>{{cite journal |first1=Janet |last1=Mullington |first2=Carsten |last2=Korth |first3=Dirk M. |last3=Hermann |first4=Armin |last4=Orth |first5=Chris |last5=Galanos |first6=Florian |last6=Holsboer |first7=Thomas |last7=Pollmächer |title=Dose-dependent effects of endotoxin on human sleep |journal=American Journal of Physiology – Regulatory, Integrative and Comparative Physiology |volume=278 |issue=4 |pages=R947–55 |year=2000 |pmid=10749783 |url=http://ajpregu.physiology.org/cgi/pmidlookup?view=long&pmid=10749783}}</ref> Somnolens er et af flere sygdomstræk eller reaktioner på infektioner.<ref name="Hart">{{cite journal |doi=10.1016/S0149-7634(88)80004-6|title=Biological basis of the behavior of sick animals|url=https://archive.org/details/sim_neuroscience-and-biobehavioral-reviews_summer-1988_12_2/page/123|journal=Neuroscience & Biobehavioral Reviews|volume=12|issue=2|pages=123–37|year=1988|last1=Hart|first1=Benjamin L.|pmid=3050629}}</ref><ref>{{cite journal |doi=10.1016/S0889-1591(02)00077-6|title=Cytokine-induced sickness behavior|journal=Brain, Behavior, and Immunity|volume=17|pages=112–118|year=2003|last1=Kelley|first1=Keith W.|last2=Bluthé|first2=Rose-Marie|last3=Dantzer|first3=Robert|last4=Zhou|first4=Jian-Hua|last5=Shen|first5=Wen-Hong|last6=Johnson|first6=Rodney W.|last7=Broussard|first7=Suzanne R.|pmid=12615196|issue=1}}</ref>
Filosofi Psykologi Søvn