Occupational Stress-Related Sleep Anomaly in Frontline COVID-19 Health Workers: The Possible Underlying Mechanisms

Abstract

COVID-19 is a highly contagious viral illness that has claimed millions of lives worldwide. Since its emergence, it has exerted a negative impact on many sectors globally without the exception of frontline COVID-19 healthcare providers. Specifically, in frontline COVID-19 healthcare workers, occupational stress-related sleep disorders such as insomnia and daytime somnolence have been extensively reported and were characterized by neuro-immunological changes. However, the possible mechanisms that underlie the sleep disorders have not been elucidated. The review was designed to highlight possible sleep mechanisms responsible for insomnia and daytime somnolence reported in frontline COVID-19 health workers. Available evidence shows that emotional perturbation, hypertension, chronobiological disruption and prolonged exposure to artificial light are among the events orchestrating occupational-stress-related sleep disorders in frontline COVID-19 healthcare workers. Anxiety-associated sleep anomaly is attributable to stimulation of the reticular activating system which occurs as a result of activation of noradrenergic fiber and sympatho-adrenal axis. Another mechanism includes depletion of hippocampal and brain glycogen by anxiety-induced activation of corticotropin releasing hormone (CRH)-secreting brain neurons and hypothalamic-corticotropic-adrenal cortex axis. Spontaneous discharge of noradrenergic fiber during basal state and changes in normal secretory rhythm of hypnosis-related chemical messengers may be responsible for hypertension- and chronobiological disruption-induced sleep disorders, respectively. Lastly, prolonged light exposure-induced suppression of melatonin secretion may elicit disruption of normal circadian sleep.