The way this should work is that during the day, light entering our eyes sends signals to the pineal gland causing a suppression of melatonin so we stay awake. When it gets dark signals cause the melatonin output to rise about 2 hours later making us sleepy. These levels peak during the night and fall off by daybreak, when we wake to another day.
However with electricity this has changed. Lighting is available all night if we want it and this often overrides the normal circadian rhythms which can be bad for our health. So melatonin supplements of 0.3 to 5 mg a day can be helpful. However melatonin is not like a sleeping pill but a chronobiotic in that it regulates circadian rhythms.
Tests show that Melatonin supplements can also be beneficial for a variety of cancers, cluster headaches, anxiety, and tinnitus as well as protection against Alzheimer’s disease although these studies are not yet conclusive.
In our forties or fifties our natural melatonin output begins to decline which seems to also match our physical deterioration of the pineal gland and by our late seventies, melatonin has dropped to very low levels. It has been observed that there are very low levels of melatonin in suffers of Alzheimer’s disease suggesting that a drop in melatonin could be an early marker for this disease. The levels get even lower as the person gets sicker.
Alzheimer’s patients usually have disruptions of normal circadian rhythms leading to strange behaviour in the evening or night so it may be useful in helping these people adjust their rhythms. Melatonin is also a powerful antioxidant so it may be useful in assisting with damage done by free radicals and oxidative stress.
Both of these are factors in Alzheimer’s because the brain is very vulnerable to these. Melatonin is very versatile and it is believed that its antioxidant protection may be related to its role as a regulator of circadian rhythms because the disruption of these promotes abnormal levels of oxidative stress. This is why it is important for the elderly to reduce the fluctuations of this hormone and especially in Alzheimer’s patients.
An advantage of melatonin over other antioxidants is that its molecular structure allows it to cross the blood-brain barrier and enter any component of the brain cells including the mitochondria. These organelles, where the brain’s chemical energy is generated, are the chief source of free radicals—and they are its chief victims. Oxidative damage to the mitochondria is thought to be an important factor in aging and dementia.
It therefore helps protect brain neurons from damage or death by oxidative stress making it important in the fight against Alzheimer’s. The melatonin protects against the destructive effects of two dangerous proteins: amyloid-beta and hyperphosphorylated tau. Amyloid-beta attacks and destroys neurons resulting in decay of the brain seen in Alzheimer’s victims. Hyperphosphorylated tau is also destructive; it’s the result of a chemical modification of a benign (and vital) protein called tau.
It is believed that Melatonin helps the formation of new neurons and tests show that rats who had melatonin lowered by haloperidol suffered problems with memory. Melatonin taken before and during the haloperidol treatment however prevented the memory loss, inhibited hyperphosphorylation of tau, and reduced oxidative stress. It was also found that fluctuations of body temperature were regulated with melatonin.
Melatonin is also known to enhance the immune system by promoting the production of T lymphocytes, a type of white blood cell that enhances the production of antibodies. It has a low toxicity and can be taken by most people in large amounts with no serious side effects although if you are on prescription drugs you need to check with your doctor. So if you are having problems with sleep or memory why not consult your natural practitioner if this supplement is right for you?