Impaired Melatonin Secretion, Oxidative Stress and Metabolic Syndrome in Night Shift Work

Abstract

Metabolic syndrome has been associated in many studies with working in shifts. Even if the mechanistic details are not fully understood, forced sleep deprivation and exposure to light, as happens during night shifts, or irregular schedules with late or very early onset of the working program, lead to a sleep–wake rhythm misalignment, metabolic dysregulation and oxidative stress. The cyclic melatonin secretion is regulated by the hypothalamic suprachiasmatic nuclei and light exposure. At a central level, melatonin promotes sleep and inhibits wake-signals. Beside this role, melatonin acts as an antioxidant and influences the functionality of the cardiovascular system and of different metabolic processes. This review presents data about the influence of night shifts on melatonin secretion and oxidative stress. Assembling data from epidemiological, experimental and clinical studies contributes to a better understanding of the pathological links between chronodisruption and the metabolic syndrome related to working in shifts.

Association between sleep traits and risk of colorectal cancer: A bidirectional Mendelian randomization study

“…Melatonin is a human hormone produced by the pineal gland, which has many functions such as regulating the circadian rhythm and increasing the immunity. Hohor et al 34 . found that the levels of melatonin and its metabolites in shift workers exposed to light at night showed a gradual decline.…”

“…Second, sleep is a key mechanism for maintaining optimal immune 37 , cellular 38 , metabolic 39 , and endocrine 40 , and each neurophysiological dysfunction is associated with carcinogenic pathways. In addition, the disorder of sleep and rest may affect the innate and acquired immune capacity, increase reactive oxygen species (ROS), lead to DNA damage and disrupt metabolic function, leading to the occurrence of tumors 34 . Not only that, some common carcinogenic factors, smoking, obesity, less exercise and other people are more likely to develop sleep disorders, which also explains the higher incidence of tumors 41 .…”