I have had an Alpha-Stim for many years. I first rented one from my sleep doctor.
It's very relaxing and can help sleep, but you have to be really patient. It takes experimenting to figure out the duration, time of day, and intensity that will help your particular condition.
I've recently started using mine again for sleep. It helps me most when I use it at night at an intensity of 1. I've found it more effective to use it every 2 or 3 nights instead of every night.
Some people use it at a higher intensity during the day. I don't have day-time anxiety, and it makes too sleepy to use it then.
I tried RTMS (repetitive transcranial magnetic stimulation) at a biofeedback clinic, but it didn't work for me. I had such extreme sensitivities that even the lowest intensity caused me a great deal of insomnia.
The biofeedback therapist had not seen any patient react as I did. Most of their patients do great with it. I might try it again sometime because I've had some improvements and am not as sensitive as I was.