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Volume 4
Clinical Neuropsychology: Open Access
Neuropsychiatry 2018
August 27-28, 2018
August 27-28, 2018 Tokyo, Japan
8
th
Global Experts Meeting on
Advances in Neurology and Neuropsychiatry
A possible link between circadian rhythm disorders and mood disorders
William W McDaniel
University of Kentucky College of Medicine, USA
S
easonal affective disorder and all the circadian rhythm disorders are related to a discrepancy between the duration of the
solar day and the circadian cycle. The circadian cycle of humans and other mammals is close to one hour longer than
the 24 hours period from sunrise to sunrise. Interestingly, birds show a circadian cycle of less than 24 hours and close to
23 hours. Terrestrial invertebrates, the insects provide the key to understanding this discrepancy. The earliest identifiably
mammalian fossils are from the Permian era strata. Insect orders that first appeared in the Permian era include the Hemiptera
(bugs), Orthoptera (crickets and grasshoppers), Coleoptera (beetles) and the Neuroptera (lacewings). All of whose modern
survivors show a circadian cycle longer than 24 hours in at least some stage of the life cycle. The insects whose ancestors first
appeared in Mesozoic strata with the birds include Hymenoptera (bees, wasps and ants) and Lepidoptera (butterflies and
moths). Their modern survivors, like the birds, demonstrate a circadian rhythm shorter than 24 hours. It is proposed here that
the duration of these animal classes’ circadian day may reflect the duration of the solar day at the time of their origin. There is
now evidence for three large meteorite impacts on Pangea near the end of the Permian era, one in Wilkes Land of Antarctica,
one near the Falkland Islands, and one just west of Australia. The eastward movement of the Australian, African, and Eurasian
continent/plate and the southeastward movement of the Antarctic continents/plates suggest that those meteorites were moving
eastwards and struck the planet obliquely. Having done so, they might have imparted momentum to the planet’s rotation and
so accelerated it. This may mean that circadian rhythm disorders are the consequence of a change in the duration of the solar
day due to a disaster and that daytime lethargy and depression may have had adaptive value to the mammals who survived that
disaster. If this is true, it adds context to our treatment of these disorders with bright light and melatonin.
William.McDaniel@va.govClinNeuropsychol 2018, Volume 3
DOI: 10.4172/2472-095X-C1-003