From experience. Our first year here, we had a terrible storm in Winter that took the power out for about five days. Nightwolf and I mostly sat in the kitchen beside the wood/turf stove. The kitchen used to be a basement, but Ireland in Winter can be so grey and dark; even at midday, it can be hard to see with just windows.
We started with lanterns, but then the kerosene fuel ran out. So I ran out in the yard and got pebbles, put them in ceramic pudding dishes (the tiny ramekins) with some cotton string warped around the pebbles and then onto a nail. Then I got out the olive oil, and by this point, my husband wondered if I'd gone nuts. After I poured in the olive oil, I made sure the cotton string was over the nail and out of the oil. Then I lit them. Nightwolf was shocked. He said, "They give so much light!" And I said deadpan, "Yes, the entire ancient Western World was lit this way; olive oil was so valuable."
Anyway, there is a knitting part to this. I had been making scarves for various Yule presents for family back in the US—lovely fisherman's scarves (the pattern is free and still online). I was using a lovely deep blue and a sea green. Which was OK during the day, but once night hit; I realized that most traditional British Isles and many Scandinavian knitting patterns were in bold and very different colors, like black and white, red and white, or blue and white.
Because darn, if I couldn't tell the difference between either yarn by lamp light and I have a very acute color sense. It didn't matter much because the colors were close and looked good no matter what I did. It is primarily a simple knit and pearl pattern, so changing colors added an accent rather than a design.
But since then, in Winter, if the power goes out, I always start a small project like a hat (if I don't have one already) in two highly contrasting colors or just one color.
As for weaving, our friends bought an old church building in a part of Scotland called a "Weaver's Village." Even the upstairs of the church had a skylight (going back to the late 18th century) for light. Almost all the older homes built before the invention of the mechanized looms (think Luddites) were built with these skylights.
The Norse built weaving sheds outside the home, partly sunk in the ground for warmth, but then with a large open door where the great stand-up (warp weighted) looms were placed next to or across from the catch the light. In more recent times, these were stored upstairs and then brought down to weave heavy coverlets that modern (14th century and later) floor looms couldn't handle. Giant floor looms were often in the attic (done in US farmhouses, too) with some skylight or opening that could be opened in good weather to let in light.
In much of Northern Europe and Eurasia, spinning was the work of deep winter because you don't have to see very well (or at all) to do it, along with knitting (or nailbinding), which can be done without much light. Band weaving was also sometimes done because people memorized patterns on small looms. But serious weaving, sewing, and fabric construction usually took place from Spring to Fall, because of the need for good lighting.
