Abstract: Gamma brain stimulation (around 40 Hz) is performed using light pulses. To perform theta brain stimulation (around 7 Hz) without perceptible flicker, the light source is also strobed at 47 Hz (also within the gamma range). The brain perceives the 40 Hz and a subtraction frequency of 7 Hz (in the theta range). The combined gamma and theta wave stimulation of the brain may be used for preventing or treating brain disease or sleeping disorders. The particular stimulation frequencies and their phases create neuronal gamma-theta coupling in the brain that has been shown to have positive effects on memory, Alzheimer's disease, motor skills, and other functions. Other gamma and theta frequencies, creating gamma-theta coupling in the brain, are also beneficial. The phase of the light pulses is also dynamically controlled using feedback to maximize theta-gamma coupling in the brain.

Abstract: Gamma brain stimulation for preventing or treating Alzheimer's disease or sleeping disorders using light or sound is known. A strobing 40 Hz light source has been shown to cause positive effects due to the stimulation. It is an advantage to know the actual dosage of light that enters the person's eyes in order to understand the relationship between dosage and effectiveness. A camera is used to detect the subject's gaze angle, distance, pupil diameter and any other factors that affect the light power that enters the eye. A target dosage is first determined by a medical worker, such as to determine the effects of the exact same dosage on a group of similar persons, such as Alzheimer's patients. With deviations of gaze angle, distance, and pupil size from the ideal, the effective dosage is decreased. The disclosed system adjusts the actual dosage, such as session duration, based on such factors so that the final dosage received by the person is consistent and meets the target dosage.

Abstract: A phototherapeutic apparatus for emitting therapeutic light, the apparatus comprising: a first set of one or more light sources and a second set of one or more light sources; a control module configured to control the first and second set of light sources; wherein the control circuit is configured to: control the first set of light sources to generate first light, the first light varying periodically at a first brain stimulation rate; control the second set of light sources to generate second light concurrently with the first set of light sources generating the first light, the second light varying periodically at a second brain stimulation rate equal to the first brain stimulation rate plus a third brain stimulation rate, wherein the third brain stimulation rate is selected for stimulating neural oscillations at a beat frequency corresponding to said third brain stimulation rate