Yes a side job might be draining, but consider a couple things:
What might NOT be stressful, or could be combined with stuff you already do? Like, would babysitting a couple kids on a Friday or Saturday evening , where you eat dinner with them, play, and put them to bed, be stressful? Or could you find something that is "fun" and is just one weekend morning or afternoon? for example around here farmers market vendors are often looking for extra help at the Saturday morning markets, 8 am to noon, boom, done for the weekend and pretty fun. Or what about a super part time retail job that you could go straight to after work, just pack a dinner and work it twice a week, for example? This might be a great holiday season option that wouldn't require a long term commitment to extra work.
How long have you been in your job? Long enough that you can start applying for other higher paying jobs? If its been 3 to 5 years, start checking out other options closer to home- less because of your gas cost, more because you will wear your car out much more slowly, and give yourself hours back in your day.