Not Medical Advice: According to the Mayo Clinic, melatonin increased heart rate and may cause abnormal heartbeat.
Melatonin may also cause aggression, amnesia, bedwetting (in children), body pain, changes in body temperature or feeling cold, changes in cholesterol levels, changes in the immune system, chest pain, confusion, delusions, disorientation, dizziness, eye damage or glaucoma (increased eye pressure), fatigue or irregular sleep-wake schedule, fogginess, hallucinations, headache, hormonal effects, hyperactivity, increased seizure risk (particularly in children), inflammation, insomnia, irritability, mood changes, muscle control problems or weakness, musculoskeletal disorders, nightmares, nighttime awakening, poor sleep quality, psychotic symptoms, skin reactions (flushing, itching, painful lumps, paleness, and rash), sleepwalking, slow reaction time, stomach or intestinal disorders (changes in appetite, cramping, diarrhea, esophagus inflammation, nausea, odd taste in the mouth, stomach pain, and vomiting), weakness, worsened behavior, and yawning.
It may also affect blood pressure and blood sugar levels.
Melatonin is a hormone secreted by the pineal gland, a small gland in the brain that helps control our sleep and wake cycles. Very small amounts of it can be found in foods such as meat, grains, fruits, and vegetables. It is also available as a supplement.
Check out Twelve Simple Tips to Improve Your Sleep shared by Healthy Sleep.