Nothing new or different or something we do not know here, everything is dose dependent. Look at Natrum muriaticum: from the incredibly deep changes it can create in potentised form to the needed electrolyte for life, to the toxicity of high quantities ingested daily, you have the whole gamut. Look at any remedy that is present in multiple different methods, from homeopathy, to flower remedies, to herbal tinctures, to Gemmos, to toxic poisons (quite a few examples in my Gemmotherapy book BTW) and you can see it clearly.
Potentised melatonin could be a temporary fix for some form of insomnia where no other cause can be found. Here is what I found in Murphy:
MELATONIN
(Pineal Gland Hormone)
PHARMACY - melat. Melatonin. A pineal gland hormone. Historical dose: Tincture and all potencies.
CLINICAL - Amnesia. Breast, cancer. Cancer. Chronic, fatigue. Constipation. Depression. Drowsiness. Fatigue. Headaches. Hyperactivity. Infertility. Insomnia. Jet lag. Memory, weakness. Night, terrors. Nightmares. Night watching. Seasonal Affected Disorder. Sleep, disorders. Sleep, loss.
HOMEOPATHIC - Melatonin is a hormone made by the pineal gland. Melatonin has been used as a treatment for a number of conditions, including jet-lag, seasonal affective disorder (SAD), depression and cancer.
Jet-lag, the desynchronization of the biological clock, drastic changes in the sleep-wake cycle. Night terrors. Fatigue, early awakening or insomnia. Daytime drowsiness. Ailments from loss of sleep. Chronic fatigue.
Headache, fuzzy thinking, irritability. Dizziness. Mild depression. Low sex drive. Reduced immunity. Low blood pressure. Nausea. Vomiting. Abdominal cramps. Constipation.
Side effects from melatonin are not uncommon, even at doses that are significantly less than the recommended amount. When side effects from melatonin do occur, they may include an increase in blood pressure, fatigue, depression and problems with fertility.
MIND - Confusion. Dullness of mind. Memory weakness. Hyperactivity. Irritability. Depression. Seasonal Affected Disorder. Ailments from nursing loved ones.
BREASTS - Breast cancer in women who sleep irregular hours, sleep with lights on, or work late hours, night shifts.
CAUSATIONS - Sleep deprivation. Ailments from nursing loved ones.
FEMALE - Infertility.
HEAD - Headaches.
HEART - High or low blood pressure. Stroke.
MODALITIES - Worse loss of sleep. Worse working night shifts. Worse irregular sleep patterns. Worse sleeping with lights on. Worse during winter.
RECTUM - Constipation.
SLEEP - Daytime drowsiness. Insomnia. Severe sleep disorders. Sleep deprivation. Altered sleep patterns. Sleep with lights on or work late hours, night shifts. Vivid dreams. Nightmares.
STOMACH - Nausea. Vomiting.
RELATIONS - Compare: Cocc., Carc., Luna., Coff., Nux-v., Sep.
REFERENCES - Murphy.
Dr. J. Rozencwajg, NMD
"The greatest enemy of any science is a closed mind"
www.naturamedica.co.nz