How detrimental is low-dose THC?

I've struggled with insomnia ever since getting long covid a few years ago but the last few months, I've been taking a low dose of THC to fall asleep and I've had the most success both falling and staying asleep since before long covid started. I take a low enough dose that I usually don't feel high, just a little more relaxed. However, I've heard that long-term THC use can have a bunch of side effects, especially on cognitive function so I was wondering just how detrimental is low-dose THC?