Pain is generally an unpleasant feeling in response to an event that either damages or can potentially damage the body's tissues. There are four main steps in the process of feeling pain: transduction , transmission, perception , and modulation .  The nerve cells that detect pain have cell bodies located in the dorsal root ganglia and fibers that transmit these signals to the spinal cord.  The process of pain sensation starts when the pain-causing event triggers the endings of appropriate sensory nerve cells . This type of cell converts the event into an electrical signal by transduction. Several different types of nerve fibers carry out the transmission of the electrical signal from the transducing cell to the posterior horn of spinal cord , from there to the brain stem , and then from the brain stem to the various parts of the brain such as the thalamus and the limbic system . In the brain, the pain signals are processed and given context in the process of pain perception . Through modulation, the brain can modify the sending of further nerve impulses by decreasing or increasing the release of neurotransmitters . 
I was actually diagnosed as infertile due to a lack of ovulation…. which I decided on my own was wrong. I’m an herbalist, so I’ve spent the past 7 years intensively studying the herbs used for hormonal balance both because I so desperately wanted to have children… and I think ultimately I was meant to share my journey. At any rate, what I found out on my own once away from the doctors was that I had a progesterone deficiency… I suspect this is a hormonal imbalance that can start in the womb, so it might be interesting to take a look at your mom and grandma if you still can. A big tip off for me, besides the short luteal phase was the brown discharge that occurred in my monthly flow. Ironically, I always thought that was normal because my mother had always had it as well. It’s a big sign that your progesterone is not sufficient to fully flush your uterine lining the month before and your womb is just constantly trying to get rid of left over blood each succeeding month. My mom also had a number of miscarriages and I was the only pregnancy to go full term. What’s great about this little symptom is that as I achieved balance, I could very clearly see a different cycle- one that was red from end to end. After a couple years working with the herbs (and a whole foods diet of course) I had my first child… and then I got pregnant by surprise about 18months afterwards! I believe I can see some symptoms of my chronic low levels returning- though my cycle remains red… so I’m going to have to start back into my routine.
In seasonal affective disorder (SAD) is associated with winter depression Typically, these individuals not only feel depressed they also feel tried, slow down, and generally oversleep, overeat, and crave carbohydrates in the winter. In the summer, these same patients feel very good and maybe even are elated, active, and energetic.
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Although many variables may be responsible for SAD, insufficient light exposure is the most logical explanation. Many mammals exhibit seasonal variations in activity level, sleep patterns, and appetite and are extremely sensitive to changes in day length. The antidepressant effects of full-spectrum light therapy have been demonstrated in well-monitored, controlled studies in SAD. The antidepressant effect of light therapy is probably due to the restoration of proper melatonin synthesis and secretion by the pineal gland, leading to reestablishment of the proper circadian rhythm. Full-spectrum white light (10,000 lux) is prescribed for at least 30 minutes every day in the morning. Or, better yet, use full-spectrum lighting throughout the indoor environment.