I used to live in Alaska. I don't believe any system of yoga will work with the loss of light. You are better off getting a "narrow band ultraviolet B (UVB) light" and have it facing a wall, not direct to you. It's used in the Psorisis and Vitigilo (Leukoderma for those who are in India) community, it does cause suntans and is much more intense than the sun, so indirect only, no staring at it. That will help with the physical withdrawls of needing UV activation to create Active Vitamin D.
Also get a cheap natural sunlight lamp off the net. This doesn't have UVB frequencies in it, but is more for psychological and aesthetic purposes. It gives peace of mind.
As to coldness, I'm aware of a few Tibetan techniques, but the one I figured out in Alaska and had confirmed by the webmaster of innerfire.nl, a website dedicated to Wim Hof, the Ice Man, is breath control. In my unit I was always the quickest to shiver when going out to winter morning formations at 6 AM in Alaska. But I was also the one who lasted the longest outside with the least on. I practices breathing out less than I breathed in, and holding the breath in. It allowed me to adjust pretty well after the initial shock. However, I didn't usually practice the cold water treatments Wim Hof did. My unit was notorious for wintertime river crossings in just shorts and not changing afterwards and did teach this skill to a guy I was mentoring going into the military, as seen in this december of whatever year that was (2009 or 2008):
No leaves on the trees, made him wear my old PT uniform for 24 hours hiking, and we swam across this creek at the very beginning of it.
It's purely psychological, the fear of numbness and possible frostbite. Temperature regularly plunged below zero and I kept an eye on him. It's one of the things you learn in the Alaskan Infantry to overcome.
Now am I going to sit in a puddle of water on a winter mountain covered in frost like Wil Hof does? Nope. At some point my nuts will freeze to the ground.
You'll also find videos of russian military exploring cold weather yoga, and they do a pretty good mimick, but sitting there huffing and puffing and shaking violently won't last very long. You gotta learn to increase your internal temperature. That's all breath control and getting over your fear of the cold. Hof dkes additional training like breath control in freezing cold showers, but my nuts don't like that.
As to the spiritual yogic dimension of me being able to run naked for prolonged periods of time outside in -10F weather wearing just boots, or lasting multiple winters in prolonged darkness, I dunno. If you are hurting, get a UVB lamp. Cheap ones do exist (some lizards need them too), but look the specs over very carefully. Sometimes they list the precise wavelengths or use wavegraphs, learn to interprete them.
