Is melatonin supplementation safe for individuals with cardiac risk?

Melatonin and Cardiac Risk

Melatonin is safe for individuals with cardiac risk and does not worsen cardiovascular outcomes; in fact, it may provide cardioprotective benefits through antioxidant and anti-inflammatory mechanisms. 1

Safety Profile in Cardiac Patients

Major cardiovascular societies including the American Heart Association, American College of Cardiology, and Heart Failure Society of America do not list melatonin as contraindicated or harmful in patients with cardiac disease. 1 This absence from warning lists is particularly meaningful given these organizations explicitly identify harmful medications in heart failure patients. 1

The Society for Perioperative Assessment and Quality Improvement recommends continuing melatonin through the perioperative period in cardiac surgery patients, demonstrating confidence in its cardiovascular safety. 1 A prospective trial in 500 cardiac surgery patients showed melatonin reduced postoperative delirium without cardiac complications. 2

Evidence Supporting Cardiovascular Safety

A randomized controlled trial specifically examined melatonin's effects on sleep-disordered breathing in 60 patients with coronary artery disease (CAD). 3 Patients received 5 mg melatonin daily for 30 days, and Holter ECG monitoring showed no worsening of apnea-hypopnea index (mean change +1.2 ± 11.3 in melatonin group vs +1.0 ± 9.0 in placebo, p=0.44). 3 This is clinically significant because sleep-disordered breathing is a major concern in cardiac patients, and melatonin did not aggravate this condition. 3

Potential Cardioprotective Benefits

Beyond safety, emerging evidence suggests melatonin may actively benefit cardiovascular health through multiple mechanisms:

• Antioxidant effects: Melatonin acts as a direct free radical scavenger, protecting cardiac tissue from oxidative stress. 4, 5

• Blood pressure reduction: Melatonin decreases blood pressure through effects on the hypothalamus, catecholamine reduction, and smooth muscle relaxation in the aorta wall. 6 Even 1 mg doses reduced blood pressure and catecholamine levels within 90 minutes in human subjects. 6

• Lipid profile improvement: Melatonin suppresses cholesterol formation by 38% and reduces LDL accumulation by 42%. 6 Patients with high LDL-cholesterol have been found to have low melatonin levels. 6

• Ischemia-reperfusion protection: Animal studies demonstrate melatonin prevents cardiac muscle death following ischemia-reperfusion injury and may prevent cardiac hypertrophy. 4

Clinical Observations in Cardiac Disease

Patients with coronary heart disease have demonstrably low melatonin production rates, especially those at higher risk of cardiac infarction or sudden death. 6 Similarly, individuals with hypertension have lower melatonin levels than those with normal blood pressure. 6 These observations suggest melatonin deficiency may contribute to cardiovascular pathology rather than melatonin supplementation posing risk. 6

Recommended Dosing for Cardiac Patients

Start with 3 mg of immediate-release melatonin taken 1.5-2 hours before bedtime. 7, 1 This timing optimizes circadian effects. 7

• If ineffective after 1-2 weeks, increase by 3 mg increments up to a maximum of 15 mg. 7, 1
• Lower doses (3-5 mg) are preferred as higher doses (10 mg) may cause receptor desensitization and more frequent adverse effects including morning headache and sleepiness. 7, 1

Critical Drug Interactions and Precautions

Use caution in cardiac patients taking warfarin due to potential interactions. 1 This is the primary cardiac-relevant precaution identified by the American Academy of Sleep Medicine. 1

Additional considerations for cardiac patients:

• Choose United States Pharmacopeial Convention Verified formulations to ensure reliable dosing and purity, as melatonin is regulated as a dietary supplement with variable quality. 7, 1
• Exercise caution in patients with epilepsy based on case reports. 1
• Monitor glucose tolerance in diabetic cardiac patients, as melatonin has been associated with impaired glucose tolerance after acute administration. 1
• Avoid in patients with dementia and irregular sleep-wake rhythm disorder due to lack of benefit and potential harm. 7

Common Pitfalls to Avoid

• Don't use excessive doses: Higher doses are not more effective and cause more side effects. 7 The most frequently reported adverse events are headache (0.74%) and dizziness (0.74%). 7, 1
• Don't take melatonin in the morning or afternoon: This worsens circadian misalignment. 7
• Don't expect long-term data: Safety data beyond several months is limited, though available evidence suggests good tolerability. 7, 1
• Don't assume all formulations are equivalent: Product quality varies significantly; choose verified formulations. 7, 1

Duration of Treatment

For chronic insomnia, limit melatonin use to 3-4 months maximum due to insufficient long-term safety data. 7 However, for circadian rhythm disorders, longer-term use may be appropriate with periodic reassessment every 3-6 months. 7 Studies in cardiac surgery patients used 30-day courses safely. 3