For those who are unaware, melatonin is a hormone produced deep in the brain (the pineal gland) and helps to regulate our sleep / wake cycle, among other things. Sunlight hitting the back of the retina shuts down the production of melatonin, while the onset of nighttime will allow the body to release more melatonin. So what does this have to do with depression?
We’ve all heard of serotonin and the drugs like Prosac and Paxil and Zoloft that affect serotonin use in the brain. These are generally used to treat depression, but, in a close review of the studies that have been done, their effectiveness over placebo was minuscule. Of course, in these same studies, the placebo had a powerful effect on the patient’s depression, meaning that anyone responding to these drugs is probably benefiting from a placebo response and not the drug itself.
Melatonin and serotonin are players along the same pathway; thus, what effects one pathway will influence both hormones. It is for this reason that there is rising interest in drugs that modify melatonin levels to affect depression. The drug companies know that these current financial blockbuster drugs, if the curtain is ever pulled back, could fall like a house of cards. So they are looking elsewhere.
The biochemistry is pretty straightforward; there is only a single step between serotonin and melatonin production in the pineal gland. The pathway starts with the amino acid tryptophan (or 5-HTP, which is the next compound produced and can be very effective for depression or anxiety). As would be expected, serotonin levels are higher during the day, but production shifts to melatonin as night falls.
So what does this mean? It ties in stress, sleep hygiene, anxiety and depression into a biochemical pathway. Stress levels will lead to a rise in cortisol levels later in the day, making it hard to fall asleep. Problems sleeping may lead the sufferer to be exposed to bright lights when the body really should be producing more melatonin. Less melatonin production will interfere with the smooth flow through the biosynthetic pathway, leading to depression.
In addition, melatonin levels have been linked to things like migraines, seizures and cancer. Rest assured that these conditions will be impacted as well.
The bottom line is that stress management and proper sleep are an integral component of any healthy lifestyle. Sleep medications do nothing to fix the elevated cortisol, and will likely disrupt the synthesis of melatonin, further throwing off the cycle. Stress needs to be managed with any number of tools available so that sleep patterns can be restored.