Twenty studies were included (n=608, range four to 108): three randomised controlled trials (RCTs) (n=152); two controlled trial s (n=49); and 15 pre/post studies. Two RCTs and one CT were blinded.
Cognition (nine studies, n=251)
A crossover RCT of a single session of theta stimulation in four healthy adults reported no significant improvement in verbal fluency or attention associated with the intervention and a reduction in immediate recall. Controlled comparisons reported significant benefit from the intervention in all three outcomes measured. Six pre/post studies reported significant benefit from the intervention for 19 of 28 cognitive outcomes.
Stress (seven studies, n=212)
One RCT (n=108) showed significant reduction in anxiety from a single session of alpha/delta therapy for day surgery patients. A crossover RCT of a single session of theta stimulation in four healthy adults reported significant improvement from the intervention in one of five measures. Five pre/post studies reported significant benefit from the intervention for 16 of 27 outcomes.
Pain (two studies, n=59)
One RCT (n=40) reported significantly reduced pain among patients who had photic stimulation during surgery. One pre/post study reported significant benefit from the intervention for 23 of 24 outcomes.
Headache and migraine (three pre/post studies, n=90)
Photic stimulation was effective for treating or preventing migraine in two studies and for treating muscle pain in two studies. One study found it ineffective for migraine or sinusitis.
Mood (three studies, n=41)
A crossover RCT of a single session of theta stimulation in four healthy adults reported no significant effect from the intervention. One controlled comparison and one pre/post study reported no benefit from the intervention in any of 15 outcomes.
Behaviour (two pre/post studies, n=57)
Two pre/post studies of children with behaviour problems found significant benefit from the intervention for 16 of 39 outcomes.
PMS (One pre/post study, n=50)
Photic stimulation was associated with significant relief of PMS symptoms.
A summary of findings for specific brainwave entrainment frequencies was also reported.