There seems to be conflicting information available about whether or not it's good to exert in your yoga practice in winter. I've found articles - and myself used to - advise a restful restorative practice only during the winter months. And winter evenings are the perfect time for a cozy yin or restorative session, for sure.
But recent research, within the past 20 years, has pointed towards favoring exertion during the winter months. From an Ayurvedic perspective, the body is building kappha tissues now if everything is working well. This means muscle, bone and immune response. In fact, this is when all doshas are most balanced and we have an opportunity to build health and well being.
In fact, the body's immune response is heightened in the winter, with elevated serum levels of C-Reactive Protein and InterLeukin-6 - meaning inflammation is on the rise. Ayurveda would say this is kappha building. Strenuous exercise mitigates the inflammation while putting it to use - inflammatory molecules do have jobs to do.
Additionally, your pineal gland is producing far more melatonin in the winter, and melatonin aids in muscle building and protects against damage from all those inflammatory molecules and immune responses. Additionally, melatonin is protective against oxidative stress that can accompany strenuous exercise. This is especially protective for cardiac muscle.
This just makes sense: we're sleeping more with more hours of dark. If we also only rest in our yoga practice, it's an invitation to Seasonal Affective Disorder to move in. However, if we can sweat and groove in the morning, rest in yin and restorative postures in the evening - for even 15 minutes - we have the perfect antidote to SAD, inflammation and cough and cold season.
So here's to Sun Salutations in the morning and some restful yin and restoration in the evening! Focus on backbending postures for a little extra boost.