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Why do some people secrete more melatonin than others?

Burgess H; Alderson D; Fogg L; Eastman C
Sleep 2007 Jun; 30(Abstract Suppl):A49
Introduction: Melatonin is secreted from the pineal gland at night. Low levels of melatonin are associated with greater risk for cancer and cancer growth. Thus, we looked for factors that influence melatonin levels. Methods: Melatonin secretion (area under the curve, AUC) was estimated from baseline melatonin profiles derived from saliva samples collected half-hourly for 20 hours in dim light (<10 lux) from 85 males and 86 females. Subjects were young (18-45y) nonsmokers with no medical, psychiatric or sleep disorders, and were medication free (except hormonal birth control, n=15). Prior to saliva collection subjects abstained from alcohol for at least 24 hours, and avoided NSAIDs and were on fixed sleep schedules for at least 3 days. Results: Peak melatonin levels ranged from 2.4 to 83.6 pg/ml. AUC ranged from 88 to 2126 pg/ml/h. Females tended to secrete more melatonin (p=0.06), because hormonal birth control increased melatonin (p=0.024). Drinking 10 or more alcoholic drinks per week was associated with secreting less melatonin (p=0.02). Full-time workers secreted less melatonin (p=0.03) than students, part-time workers and those unemployed. Definite morning types secreted less melatonin than other morningness-eveningness types (p=0.047). There was a trend for people who wore eyeglasses and/or contact lenses to secrete more melatonin (p=0.06, p=0.07) than people without corrective vision. There were no significant associations between melatonin secretion and race, education, Epworth, PSQI, MMPI-2 scores, and the presence of bed partner and/or housemate. Conclusion: Several factors may influence melatonin levels. Potential mechanisms include that full-time workers and definite morning types may receive light that suppresses their melatonin, and that this photoperiodic history is reflected in their subsequent dim light melatonin profiles. UV filters in corrective vision may reduce exposure to short wavelength light which can suppress melatonin. The causes of the large variation in melatonin levels remain unknown and are probably genetic.
Sleep-deprivation; Sleep-disorders; Shift-work; Circadian-rhythms; Psychomotor-function; Workers; Work-environment; Work-capability; Work-performance; Humans; Men; Women; Accidents; Injuries; Education; Shift-work
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Rush University Medical Center, Chicago, Illinois
Page last reviewed: May 11, 2023
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