As summer turns to fall, we adjust to shorter days. The natural harvest in most temperate climates promotes carb-loading so we can store energy for the winter. This energy storage also influences when babies are born. Plus, our internal clocks, run by hormones and melatonin, can help dictate reproductive cycles.
Seasonal Living and Energy Storage
September is when fruits and vegetables are the most bountiful. Farmers are harvesting all of the goodies from their crops and delivering them to stores and markets. They are also preparing for the down season and for the cold air that is slowly creeping in.
If we ate only from the seasonal harvest (as our ancient ancestors did and most mammals still do), we would be loading up on these fruits and veggies… with a purpose!
The carbohydrates attained from produce would induce a blood sugar spike and, in response, our insulin levels would rise in order to deliver the carbs as blood sugar to our brains, muscles, and fats, and, ultimately, boost hormone production.
As summer carb-loading peaks in September, the body becomes naturally insulin resistant—meaning muscle cells cannot consume one more calorie of sugar. Excess sugar begins to store as fat.
This storage of fat provides the insulation needed and energy reserves required for the winter-spring “famine” waiting around the corner.
For reasons related to energy storage, September is also mating month for most mammals. This allows for babies to be born in early summer, giving them ample time to grow and gain some fat to endure the next fall and winter.
Melatonin’s Role in Seasonal Mating
Melatonin, which connects us to the daily and seasonal cycles, regulates most of our hormones, including sex hormones. Having a baby in early summer requires most mammals to mate in late summer–most commonly in September.
Our bodies produce Melatonin at night, after the sun sets. As the sunlight lingers for longer during the summer, melatonin levels tend to be suppressed. Meaning we produce more melatonin in the winter, when the nights are longer.
The prolonged night times during winter release of melatonin, which acts as an endocrine signal for de-activating the hypothalamic gonadotropin-releasing hormone. That hypothalamic gonadotropin-releasing hormone is required for pregnancy. (High levels of melatonin have well-documented birth control properties.)
For seasonal breeders, September is the last chance to conceive before the surging melatonin levels block conception.
In nature, sex hormones rise when insulin rises, and blood sugars and insulin both surge in the summer and fall, when melatonin levels are still low.
During these end-of-summer days, blood sugar, insulin levels, cortisol, serotonin, and sex hormones are surging as mammals prepare to fight for the right to reproduce.
Serotonin thickens the blood for better clotting and constricts blood vessels, so if mammals are injured during the rut, their bodies are literally ready for a fight.
As serotonin falls after sex, dopamine rises and reward and pleasure hormones surge.
Like a circadian symphony, these changes in September are followed by less light and longer nights. Melatonin levels surge, and the thought of sex is replaced with the desire to sleep.
Bringing (Seasonally) Sexy Back
In the natural world, when September rolled around, we would be gorging on carbs, getting ready to mate, storing fat, and reserving fuel, Clearly, we have evolved away from being seasonal breeders, but the seasonal hormonal shifts, albeit not as pronounced as they may have been thousands of years ago, are still present inside all of us.
When the sun sets in September now, you likely turn on lights and keep them on for an average of six hours before going to bed. That is six hours less of melatonin production.
This September, give yourself permission go to bed early and eat fruits, veggies, and grains (if your digestion permits) (then minimize these during the winter and spring).
It all starts now… so get ready and enjoy the last month of summer!
See also Sex on the Road Less Traveled