Melatonin also has an effect on a female's menstruation cycle. Since the female's menstrual cycle actually "mirrors" the moon cycle, it's no surprise that the timing of ovulation is dependent on proper daytime and nighttime exposure (and not being boarded up all day in an artificially-bright office.)
Over the past few months while I was supplementing with high doses of melatonin (10mg a night! A typical dose is between 1-2mg,) I slept like a freaking baby. Within 20 minutes of popping one of those pills, I was immediately dozing off and actually managed to turn my brain off. No more racing thoughts of muscle insertions and origins during my physical therapist assistant program! Hurrah! With supplementation, I only woke up 1-2 times a night verses waking up 4-6 times a night without the assistance. In addition, it was easier to fall back asleep and stay asleep. In the most stressful period of the program, I believe I was supplementing with melatonin about 5-6 days a week, if not every single night. And this continued... for months.
Fast-forward 16 months later, and I am successfully a PTA graduate. I also successfully gained almost ten pounds. For reference, I have always been a thin girl. At my leanest and even my healthiest, I maintained below 110lbs with boundless energy. I slept naturally well, I wasn't stressed, I woke up everyday eager to exercise and get outside (primarily body weight exercises and Crossfit-esque workouts), and I was eating practically limitless amounts of whole, natural foods. I was flyin' high. And despite academic and financial stress devouring me during my later months as a PTA student, I tried to stay as healthy as possible. In fact, this is where maintaining my health mattered MOST. I went outside and "played" less, but I still ate clean, healthy portion-sized paleo meals and attended the gym three times a week. My training focused on 45-60mins of heavy lifting (squats, lunges, rows, deadlifts, chin-ups, push-ups, etc.), plus an average of 6-15 miles of bike riding per week. I now weight about 117lbs. Now I'm not complaining, and I'm sure a few of those pounds were muscle. But it did come as a little surprise to me. In addition, my menstrual cycles were all over the place. I'd get them, eventually, but they were incredibly sporadic.
Regardless, I still love you, Swanson Vitamins!
Research shows that animals injected with melatonin can either gain weight OR lose weight, depending on the species. In humans suffering from SAD (Seasonal Affective Disorder), melatonin seems to speed up the metabolism.
However, recall that SEROTONIN is necessary to convert into MELATONIN. If an individual requires melatonin to sleep at night, more than often they are deficient in serotonin because the conversion simply cannot take place. A lack of serotonin has a direct effect on increasing appetite, particularly for carbohydrates. Taking supplemental melatonin will NOT re-establish healthy serotonin levels. In this case, melatonin isn't exactly the cause of an increased appetite (and thus weight gain), but could be masking a bigger problem that needs to be dealt with directly.
How do you naturally increase serotonin levels? Expose yourself to sunlight for an average of 20-60 minutes everyday, preferably upon waking. In one study, thirty-six people with SAD were exposed to a light box consisting of 2,500 lux. In two weeks, they were eating 50% fewer carbohydrates during the second half of the day than they had prior to therapy. I have to admit, during my program, I got out in the sun a lot less...
Consider this phenomena from an evolutionary perspective. In the dead of winter, there is less food available. Biology tells us, "store more fat!" Which macro nutrient is most efficient at fat storage? Carbohydrates, due to the surge in storage-hormone insulin. It's no mistake that high-carb root vegetables and tubers, such as sweet potatoes, squash, and pumpkin, grow in the preceding months to winter. In evolutionary times, these starchy foods are introduced at the prime moment to initiate fat storage for the colder months when there is less food supply.
Another piece of the puzzle is the effect that melatonin has on the THYROID. The thyroid is a major player in metabolism, and pathologies associated with the thyroid can either be HYPERTHYROIDISM (overactive thyroid, with an increase in metabolism), or HYPOTHYROIDISM (under active thyroid, with a decrease in metabolism.) Melatonin is suspected to DOWN-REGULATE the activity of the thyroid gland, therefore exacerbating any issues with a sluggish thyroid. What else may contribute to a sluggish thyroid? Chronic calorie restriction (which a lot of females do!) Incidentally, when I'm stressed, I tend to eat LESS (weird, I know,) regardless of increased activity. Thyroid problems also run rampant on my father's side of the family in all the females. Great!
So, can we make the conclusion that melatonin definitely causes weight gain? Unfortunately, the literature still looks a little weak. Regardless, there are theories pointing to this phenomena, and obviously quite a few personal experiences floating around the web. As for me, I'm saying FAREWELL to daily doses of melatonin. Not just because I'm curious if I'll get to my "pre-melatonin" weight, but I now understand the potential ramifications of orally taking melatonin for the long term.
Do you take melatonin? Have you noticed any changes in your weight, appetite, mood, sleep behaviors?