I have the exact same issue. I need sleep but some times struggle with it when fasting. I also take Ashwagandha. I take it as a tincture and add a few drops to my tea. I haven’t noticed it helping with sleep (but I wasn’t taking it with that in mind).
What has helped me the most with sleep is more magnesium and potassium, taking a hot shower before bed, using an eye mask, and listening to a yoga nidra guided meditation before bed.
I hate insomnia too. To combat, firstly, reduce caffeine, fasting I only need one half of usual amount …get some activity to drain your batteries, this helps …and if needed, 1 good puff of strong indica …zzz