These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area. Plants, just like people, need to adjust to the onset of winter.
Landscape plants go dormant.
Most houseplants do not go dormant, but the change of seasons can change their growing conditions significantly. As a result, houseplants may look unhealthy. As the home gets closed tighter for winter, and is heated, the environment around houseplants changes. Overall the air indoors becomes drier. Depending on where the plant is located, cold or hot drafts can become a problem.