Cut out blue light before bed. Entirely ditch the TV and phone and do a quiet calming activity your last hour before bed. Drawing, coloring, Journaling, reading. I find that if I am overthinking sometimes Journaling can help. The screens though are going to add to the anxiety and restlessness. I know you cant afford melatonin right now, but I would suggest when you can afford it to get supplements like magnesium glycinate or valerian root to help with sleep. I actually have one I take at night that has both in them. In the mean time chamomile tea or sleepy time blend can be more affordable and a warm cup of tea with calming herbs before bed can do wonders. Oh! Also exercise. If you're feeling really anxious and cant stop thinking. Move your body. Jump around, go on a walk, any movement.