Editing Shivering (section)

== Biological basis ==
Located in the posterior [[hypothalamus]] near the wall of the [[third ventricle]] is an area called the primary motor center for shivering.<ref>{{Citation |last=Bear |first=Matthew H. |title=Neuroanatomy, Hypothalamus |date=2022-10-10 |work=StatPearls [Internet] |url=https://www.ncbi.nlm.nih.gov/sites/books/NBK525993/ |access-date=2025-03-10 |publisher=StatPearls Publishing |language=en |pmid=30252249 |last2=Reddy |first2=Vamsi |last3=Bollu |first3=Pradeep C.}}</ref> This area is normally inhibited by signals from the heat center in the anterior hypothalamic-preoptic area but is excited by cold signals from the [[skin]] and [[spinal cord]] and becomes activated when the body temperature falls even a fraction of a degree below a critical temperature level.<ref>{{Cite web |title=Regulation of body temperature by the nervous system |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC6034117/}}</ref> The center then causes rapid contractions of skeletal muscles, producing heat as a byproduct.<ref>{{Citation |last=McCuller |first=Christopher |title=Physiology, Skeletal Muscle |date=2025 |work=StatPearls |url=https://www.ncbi.nlm.nih.gov/books/NBK537139/ |access-date=2025-03-10 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30725824 |last2=Jessu |first2=Rishita |last3=Callahan |first3=Avery L.}}</ref>

Newborn babies, infants, and young children experience a greater (net) heat loss than adults because of greater [[surface-area-to-volume ratio]]. As they cannot shiver to maintain body heat,<ref>{{Cite web |title=Muscle Non-shivering Thermogenesis and Its Role in the Evolution of Endothermy |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC5684175/}}</ref> they rely on [[Thermogenesis#Non-shivering|non-shivering thermogenesis]].  Children have an increased amount of [[brown adipose tissue]] (increased vascular supply, and high mitochondrial density), and, when cold-stressed, will have greater oxygen consumption and will release [[norepinephrine]].<ref>{{Cite journal |last=Gilsanz |first=Vicente |last2=Hu |first2=Houchun H. |last3=Kajimura |first3=Shingo |date=2012-10-22 |title=Relevance of brown adipose tissue in infancy and adolescence |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC3614088/ |journal=Pediatric Research |language=en |volume=73 |issue=1 |pages=3–9 |doi=10.1038/pr.2012.141 |issn=0031-3998 |archive-url=http://web.archive.org/web/20250204141707/https://pmc.ncbi.nlm.nih.gov/articles/PMC3614088/ |archive-date=2025-02-04}}</ref> Norepinephrine will react with lipases in [[brown fat]] to break down fat into [[triglycerides]].<ref>{{Cite journal |last=Zhou |first=Anqiang |last2=Kondo |first2=Mari |last3=Matsuura |first3=Yukinaga |last4=Kameda |first4=Kenji |last5=Morimoto |first5=Chie |last6=Tsujita |first6=Takahiro |last7=Okuda |first7=Hiromichi |date=1995-04-01 |title=Mechanism of norepinephrine-induced lipolysis in isolated adipocytes: evidence for its lipolytic action inside the cells |url=https://www.sciencedirect.com/science/article/abs/pii/092846809500004K |journal=Pathophysiology |volume=2 |issue=1 |pages=29–34 |doi=10.1016/0928-4680(95)00004-K |issn=0928-4680|url-access=subscription }}</ref> Triglycerides are then metabolized to [[glycerol]] and non-esterified fatty acids.<ref name=":1">{{Cite web |title=Triglycerides |url=https://eclinpath.com/chemistry/energy-metabolism/triglycerides/ |access-date=2025-03-10 |website=eClinpath |language=en-US}}</ref> These are then further degraded in the needed heat-generating process to form CO<sub>2</sub> and water.<ref name=":1" /> Chemically, in [[mitochondria]], the proton gradient producing the [[proton electromotive force]] that is ordinarily used to synthesize [[Adenosine triphosphate|ATP]] is instead bypassed to produce heat directly.<ref>{{Citation |last=Alberts |first=Bruce |title=Electron-Transport Chains and Their Proton Pumps |date=2002 |work=Molecular Biology of the Cell. 4th edition |url=https://www.ncbi.nlm.nih.gov/books/NBK26904/ |access-date=2025-03-10 |publisher=Garland Science |language=en |last2=Johnson |first2=Alexander |last3=Lewis |first3=Julian |last4=Raff |first4=Martin |last5=Roberts |first5=Keith |last6=Walter |first6=Peter}}</ref>

Shivering can also appear after surgery. This is known as [[postanesthetic shivering]].

In humans, shivering can also be caused by cognition.<ref>Goldstein A. (1980). Thrills in response to music and other stimuli. Physiol. Psychol. 8, 126–129.</ref> This is known as [[psychogenic shivering]].<ref>Schoeller, F., Eskinazi, M., Garreau, D. (2018) Dynamics of the knowledge instinct: Effects of incoherence on the cognitive system. Cognitive Systems Research 47: 85-91.</ref><ref>
Oka, T. (2015). Psychogenic fever: how psychological stress affects body temperature in the clinical population. Temperature: Multidisciplinary Biomedical Journal, 2(3), 368–378. http://doi.org/10.1080/23328940.2015.1056907</ref>