Influence of Melatonin on Cardiovascular and Thermoregulatory Responses to Stress

Influence of Melatonin on Cardiovascular and Skin Temperature Responses to Stress: A Randomized Controlled Trial

This study aims to evaluate the influence of acute oral melatonin supplementation on cardiovascular and skin temperature responses to mental stress. The hypothesis is that acute melatonin will lead to reduced cardiovascular and skin temperature responsiveness to acute mental stress.

This study will utilize a randomized, crossover, placebo controlled experimental approach to determine the effects of acute oral melatonin supplementation (3mg) on blood pressure, heart rate, and regionalized skin temperature responsiveness to mental stress. The study will assess beat-by-beat blood pressure (finger plethysmography), continuous heart rate (electrocardiogram), and proximal/distal skin temperature continuously at rest and in response to the Trier Social Stress Test following either afternoon melatonin or placebo ingestion in a randomized order. Participants will consist of young healthy adults.

Inclusion Criteria:

• Must be between the ages of 18-70 years old.
• All subjects will be required to abstain from exercise and caffeine for 12 h, and alcohol for 24 h prior to the experiment.
• BMI must be <30 kg/m2.
• Menstruating women will initially be tested during their early follicular phase (2-5 days after initiating menstruation) or during low hormone phase (2-5 days after initiating menstruation) if on oral contraceptives to control for potential impact of sex steroids. Post-menopausal females (>5 years) will also be included. Females must have an intact uterus and at least one ovary. Use of hormonal replacement therapy will be allowed.

Exclusion Criteria:

• Circadian rhythm sleep disorders
• High obstructive sleep apnea diagnosis determined by STOP-BANG.
• History of meeting Diagnostic and Statistical Manual of Mental health (DSM-V) criteria of major psychiatric disorder
• Unstable or serious medical conditions (heart failure, diabetes, cardiovascular disease, etc.)
• Current, or use within past month, of psychoactive (other than stable treatment with antidepressant), hypnotic, stimulant or analgesic medication (except occasional non-narcotic analgesics), beta blockers, or alpha blockers
• Shift work or other types of self-imposed irregular sleep schedules
• Habitual smoking (6 or more cigarettes per week)
• Habitual alcohol consumption (more than 2 alcoholic drinks per day)
• Pregnancy or breast feeding