Is biofeedback effective for insomnia? what kind of biofeedback works best?

Personal choice: Biofeedback is an alternative medicine treatment for insomnia; and works well if done correctly. Guided imagery can also be of benefit; as to what kind works best the answer is really a matter of personal choice. Seek out a practitioner that has experience in the field and seek the answer to this question together...Sometimes the journey is just as effective as the remedy.

Possibly: Works in few cases when cause of insomnia is anxiety, stress or depression.

My 2 cents: I'm sure some would challenge this as anecdotal, and justifiably so, but in my clinical experience of having treated approx. 10, 000 pts., the vast majority of sleep problems are not primary, but rather caused by something else, like anxiety, adhd, or mood disorders. Biofeedback may very well work, but first i'd recommend a careful psychiatric evaluation by a tenacious, experienced, diagnostician.

Yes: Biofeedback can be very helpful for insomnia. Specifically something called cognitive behavioral therapy is designed to teach you techniques that will improve your chances of falling asleep. Many psychologists offer cbt training.