Melatonin should only be taken at night, after the onset of darkness. The best time is 20 to 40 minutes before your desired bedtime. The pineal body starts its melatonin production only after it has received a signal from your eye telling it that the ambient light intensity has dropped significantly. If you are working shifts, your daily sleep cycle determines the time when to take melatonin for best effect.

· For sleep irregularities:
Start with 3 milligram Melatonin. If you think that you have regained your normal sleep cycle, you should still continue to take melatonin for at least another two weeks. This will readjust your "body clock" and you will be able to sleep normally again, even without taking melatonin.
· For disturbed or interrupted sleep:
If you are waking up repeatedly during the night, or if you wake up too early and cannot go back to sleep again, start with 3 milligram Melatonin before your normal bedtime. Continue to increase the dosage until you reach a total 6 milligrams per day.
· For jet-lag:
Jet-lag is generally caused by an interruption of your normal circadian cycle (i.e. the cycle your organism runs through during a normal 24-hour day). Very often this happens when travelling over a number of time zones within a short period of time. Flight crews and frequent travellers suffer the most from jet-lag and its side effects. West to East flights are more strenuous than vice versa.
Melatonin can help you to adjust to the new time zone at your destination quickly and effectively. Take 3 to 6 milligrams Melatonin before your normal bedtime at the new location. Continue this dosage for three to four nights in a row until your body clock has reset itself to the new time zone.
Upon returning home, repeat the whole procedure to readjust your body clock to your original time and sleep cycle.
Many people who regularly use melatonin to combat jet-lag confirm that they do not feel any of the inconvenient side effects of travelling over a number of time zones.
· For prevention of disease:
Even though Pierpaoli and Regelson do not think that the regular application of melatonin before the age of 45 is necessary, starting melatonin therapy in your thirties could still be advisable. Melatonin is a disease-fighting hormone, and as such it may contribute to prevent two of today's most common ailments - cardiac infarction and cancer. If you think you are prone to either one of these conditions, you should start melatonin therapy at an earlier age than normal, provided that your doctor agrees. According to the findings of Russel J. Reiter (see bibliography below), maintaining a normal melatonin level at all times could prevent the development of carcinogenic processes.
Furthermore, it seems to be a fact that maintaining a "youthful" melatonin level may even counteract certain hereditary pre-dispositions. If you have any worries in this respect, you should ask your doctor to give you a comprehensive blood test, checking for the level of blood lipids, cholesterols and triglycerides. In addition he should check your glucose values to see whether your insulin metabolism is working efficiently, as well as your liver enzymes, to test your liver function. Such a comprehensive blood test is not only an excellent diagnostic tool, but also enables your doctor to decide as to whether melatonin therapy should be advised. The application of melatonin supports your organism, prompting it to normalise blood values of the most important lipids, enzymes, minerals and vitamins and bringing them back to "youthful" levels.
· For the rejuvenation of your body and maintenance of a healthy condition:
This aspect of the application of melatonin will probably be the most interesting one for the largest number of people, since it is of equal significance for the healthy as well as the sick. The "melatonin replacement therapy" developed by Pierpaoli and Regelson is based on the idea of restoring the melatonin levels of people over 45 to those of their twenties. At that age, the melatonin level in the blood peaks at approximately 125 picograms (125 trillionths of a gram) per day. After that it slowly decreases until the age of 45, where a drastic drop occurs. At the age of 80 the average melatonin level is less than half of what it was at 20. Sometimes it is so low that it cannot be measured.
The strategy is to reverse this downward curve and bring the amounts of melatonin in the body back to the levels of youth by applying the correct daily dosage. A person in his or her forties needs relatively little, in his or her fifties slightly more, and so on. By providing the organism with melatonin, we can help the pineal body to regenerate itself and thus to reset the "Clock of Ageing".

Dosages
AGE MELATONIN DOSAGE
40 – 50 3 mg at bedtime
50 – 64 3 to 6 mg at bedtime
65 – 74 3 to 6 mg at bedtime
75 und älter 3 to 6 mg at bedtime
·
If you know of earlier cases of old-age ailments - like cancer, heart disease or circulatory problems - in your family, you might consider melatonin replacement therapy at an earlier age. This could prevent the development of ailments such as these, which may be based on genetic heredity. The proposed dosage for those in their thirties could be the same as shown for people between 40 and 44 years of age.
The dosages proposed by Pierpaoli und Regelson are based on normative melatonin values of ageing people - values taken from people at these respective ages and subsequently averaged - and on the amount of melatonin required to bring these values back to a youthful level. Each person is different, not only in his or her appearance, but also with respect to heredity, predisposition, eating habits, lifestyle and experience, as well as his or her immediate living circumstances. Therefore, dosages may vary slightly from one person to the next.
This does not mean that dosages have to be measured by tenths of a milligram, since they are not "critical" values. Still, the normal daily dosage should not exceed 3 to 6 milligrams. Even though some other researchers recommend substantially higher daily dosages, we agree with Pierpaoli and Regelson that sometimes "less can be more". In no case will damage or unwanted side effects occur.