Yes, you can buy it from iHerb. You`re pretty knowledgeable about shipping things to Japan, if you`re looking for something like melatonin out there, it will automatically filter out things you can`t legally import (i.e. huge bottles containing hundreds of pills) and you only have the options for the smaller quantities that customs agree with. This may come as a surprise, as melatonin is marketed as a «natural» sleeping pill (it`s even found in some foods!). In fact, our pineal glands, which are located in the brain, produce the substance themselves when the sun goes down. This melatonin triggers the «sleep» part of our sleep-wake cycle (also known as the circadian rhythm). In healthy adults, the rüd gland produces between 10 and 80 micrograms per night. Over-the-counter melatonin could help you if your body isn`t doing enough, or replace the body`s idea of when you should go to bed. It comes in doses ranging from 0.3 milligrams to 60 mg — or about a thousand times more than the body produces than at night — although the largest dose most grocers and pharmacies carry is about 5 to 10 mg.
But even 10 milligrams of melatonin can be too much. Grigg-Damberger MM, Yanakieva D. Poor quality control of over-the-counter melatonin: What they say is often not what you get. 2017;13(2):163-165. This well-designed pharmacological study from our neighbors to the north, showing that the content and purity of over-the-counter melatonin is suspect, prompts us to again demand that the U.S. Food and Drug Administration consider melatonin a drug and use all its powers to regulate it and limit its use to prescription drugs. We celebrate the medical benefits of melatonin as a chronobiotic for specific patient groups, sleep disorders, and medical conditions. The use of over-the-counter drugs has been banned for years in much of Europe, the UK, Japan and Australia. And it`s mostly prescribed in low-dose, slow-release tablets for a few weeks to treat acute insomnia — not chronic sleep problems.
Patients may be asked to take it two or three times a week rather than every night. This is because with melatonin, less may be better; Taking too much can actually disrupt our circadian rhythm and thus worsen our sleep. Oral melatonin has low and variable bioavailability. Recent research on other pathways shows that elevated plasma concentrations can be achieved with oral melatonin transmuscose while avoiding first-pass metabolism.23 Intranasal melatonin exhibits rapid absorption and high bioavailability. However, transdermal or subcutaneous injections of melatonin show variable and often slow absorption and possible skin deposits and little benefit. Studies are needed to identify the best indications, routes of administration and doses of exogenous melatonin. The information contained in this guide does not constitute legal advice and is subject to change in accordance with the latest laws and regulations of the Japanese government. We recommend that you contact the Japanese Ministry of Health, Labor and Welfare or any other official institution listed below for the latest information. Few people know that melatonin was known as an antigonadal hormone in the early 1960s.5 Doses as low as 1 μg (20 μg/kg) reduced gonadal size and fertility in various rats, mice and hamsters.