I take vitamin D 25,000mg daily and turn every light in house on wit daylight bulbs. It helps.

I bought one a few years ago and doesn’t help me at all

No I don't have one but my doctor has suggested I get one

Yes, it sometimes it works. Start at 10-15 minutes. Increase according to therapist or psychiatrist. Whichever knows more and has more experience. I'm bipolar so I need to start slowly. I need to be careful increasing cause it could cause hypomania and/or mania episode. My therapist guides in how much time in a day. Also, try to use earlier in the morning.

I use one for an hour in the morning. I think it helps.