It becomes like a catch 22...no sleep makes you more stressed which gets in the way of sleep which makes for more stress which ...
I've been there. When my depression/panic attack first hit I didn't sleep for 3 weeks which made what should have been my waking life unbearable. After working with my GP on finding a sleep med that would work I asked for a sleep study and it turned out I have sleep apnea. I use a CPAP and that, with sleep meds, helped greatly.
Every so often I struggle with sleep, but it's usually related to what's going on and dreaming. I am going in for another sleep study to see if my CPAP settings need to be adjusted - I've been struggling with sleeping again and an adjunct sleep med isn't helping the way it should.
Also, if I can't sleep because my mind won't stop I use a mantra. As I inhale I focus on word "sooooooooooo" extending it for the entire inhale and as I exhale I focus on the word "hummmmmmmm", again extending it for the entire exhale. By focusing on my breathing and on these words I can usually fall asleep.

Good luck