**10. Occupational stress-related sleep disorders IN frontline health workers during COVID-19 pandemic: roles of hypertension**

Among the frontline healthcare workers recruited by Gupta et al. [98] 28.8% who had no history of hypertension were reported to be hypertensive during COVID outbreak. Gopal et al. [99] measured blood pressure among frontline male healthcare workers especially those whose body fat was 26.06. The study results showed that 52.4% of these people exhibited stage I hypertension with a heart rate of 92.5 BPM.

Evidence abounds on how hypertension may impair normal hypnosis. In animal studies, spontaneous hypertensive rats were shown to exhibit fewer quiet sleeps and paradoxical sleep, very mild accumulated REM and NREM sleep, and more transition from quiet sleep to active waking when compared to Wistar rats [100]. They also have lower R-R interval, higher low frequency/high-frequency ratio, higher low frequency, and lower high frequency during REM sleep when compared with Wistar rats [100]. Norepinephrine and epinephrine are excitatory neurotransmitters in the cerebral cortex and the neurotransmitter mediates wakefulness, consciousness, and alertness. Increased concentration of norepinephrine in body fluid including cerebrospinal

*Occupational Stress-Related Sleep Anomaly in Frontline COVID-19 Health Workers… DOI: http://dx.doi.org/10.5772/intechopen.109148*

#### **Figure 1.**

*Connection between occupational stress-induced emotional perturbation (anxiety) and sleep disorders in frontline COVID-19 healthcare providers. Activation of noradrenergic neurons and sympatho-adrenal axis by anxiety leads to increased secretion of epinephrine and norepinephrine, neurotransmitters which stimulate reticular activating system, and result in increased wakefulness. Furthermore, Hypothalamo-hypophyseal-adrenal axis and CRH secreting brain neurons become activated by anxiety resulting into inhibition of spontaneous thalamic reticular discharge and lowered hippocampal and brain glycogen. This then culminate into decreased non rapid eye movement sleep and increased light sleep.*

fluid [101] could lead to sleep problems. Increased norepinephrine and serotonin in the brainstem and adrenal epinephrine and norepinephrine might be implicated in high blood pressure induced insomnia [102]. In adult spontaneous hypertensive rats, hypertension is mediated by selective stimulation of the intermediolateral area, locus coeruleus and peripheral sympathetic nerves [103]. Once these areas are activated, the ascending reticular activating fibers become active leading to increased awareness and impaired hypnosis. Noradrenergic fibers are one of the examples of ascending reticular activating fibers. Studies by Russell et al. [104] revealed noradrenergic neurons are activated while inhibitory dopaminergic neurons are suppressed in spontaneous hypertensive rats. Therefore, in hypertensive cases, spontaneous discharge of noradrenergic fibers during basal state may explain how hypertension causes insomnia in frontline COVID-19 healthcare workers.
