…and higher blood serotonin levels are associated with enhanced mood. Get chewing!
I learned about this fact from:
Mohri Y, Fumoto M, Sato-Suzuki I, Umino M, Arita H. Prolonged rhythmic gum chewing suppresses nociceptive response via serotonergic descending inhibitory pathway in humans. Pain. 2005 Nov;118(1-2):35-42. Epub 2005 Oct 3.
Williams E, Stewart-Knox B, Helander A, McConville C, Bradbury I, Rowland I. Associations between whole-blood serotonin and subjective mood in healthy male volunteers. Biol Psychol. 2006 Feb;71(2):171-4. Epub 2005 May 31.