<unk> appears to cause very few side effects as tested in the short term, up to three months, at low doses. Two systematic reviews found no adverse effects of exogenous<unk> in several clinical trials, and comparative trials found the adverse effects headaches, dizziness, nausea, and drowsiness were reported about equally for both<unk> and placebo. Prolonged-release<unk> is safe with long-term use of up to 12 months. Although not recommended for long-term use beyond this, low-dose<unk> is generally safer, and a better alternative, than many prescription and over-the-counter sleep aids if a sleeping medication must be used for an extended period of time. Low doses of<unk> are usually sufficient to produce a hypnotic effect in most people. Higher doses do not appear to result in a stronger effect but instead appear to cause drowsiness for a longer period of time. There is emerging evidence that the timing of taking exogenous<unk> in relation to food is also an important factor. Specifically, taking exogenous<unk> shortly after a meal is correlated with impaired glucose tolerance. Therefore, Rubio-Sastre and colleagues recommend waiting at least 2 hours after the last meal before taking a<unk> supplement.<unk> can cause nausea, next-day grogginess, and irritability. In autoimmune disorders, evidence is conflicting whether<unk> supplementation may ameliorate or exacerbate symptoms due to immunomodulation.<unk> can lower follicle-stimulating hormone levels.<unk> s effects on human reproduction remain unclear. Some supplemental<unk> users report an increase in vivid dreaming. Extremely high doses of<unk> increased REM sleep time and dream activity in people both with and without narcolepsy.
Melatonin 
Etoperidone
Sertindole
Tropisetron
Zolpidem
Cilansetron
Chloracyzine
Alosetron