Yawning consistently poses a conundrum to neurologists and neuroscientists. Increasingly, evidence is found to link neurological disorders through the commonality of yawning episodes and contagious yawning. Despite discrete incidences (such as parakinesia brachialis oscitans) in brain stem ischaemic stroke patients, there is considerable debate over the reasons for yawning, with the mechanism of yawning still not fully understood. Cortisol is implicated in the stress response and fatigue; repetitive yawning may be the link between neurological disorders and with a strong correlation between yawning and a rise in cortisol levels. Evidence has now been found in support of the Thompson Cortisol Hypothesis that proposes cortisol levels are elevated during yawning . Additional data is in press, and further research is planned with longitudinal consideration to neurological disorders such as multiple sclerosis and stroke. Funding for such initiatives is currently being sought.
 Thompson, S.B.N., & Bishop, P., 2012. Born to yawn? Understanding yawning as a warning of the rise in cortisol levels: randomized trial. Interactive Journal of Medical Research, 1(5), e4:1-9. Doi: i-www.jmr.org/2012/e4/