Too much water and not enough light are the main reasons for etiolation of semps kept indoors. During the short day/low light season, under natural conditions semps are in the dark, usually covered by snow and kept cold. But in the house, they are warm and trying to grow, especially with abundant water, but do not have enough light to grow properly. If indoors over the winter, do not water and give the brightest natural light you can. If the outer leaves start to go crispy, then mist the plants. These are wild creatures that don't do well in indoor captivity.
However, one trick I've used to protect and keep fragile semps overwinter indoors that I did not trust outside was to seal the plant and whole pot in a plastic bag. That maintains a higher humidity level so the plant does not dry out but does not keep a high moisture level in the soil so it does not stimulate growth and etiolation. Still needs bright light, (no sun) though.
