Well worth the cost, but…..
Got this app after seeing it after search of brain wave apps. My initial check of it shows that the effects of the Delta hs helped my sleep. Others I guessing need to be used over a period of time to show any benefit. All in all, I’d recommend the app vut I would not waste money on the add free version. I paid for it and still get ads. Will have to they aren’t anything but a mild annoyance, but when I pay for ad free, I expect ad free. App is worth the five stars even with that, though I toyed with only giving four stars because of it.