Intermittent Light Exposures in Humans: A Case for Dual Entrainment in the Treatment of Alzheimer's Disease

 Sounds like it could be useful for stroke survivors. DEMAND YOUR DOCTOR CREATE A STROKE PROTOCOL ON THIS.

Intermittent Light Exposures in Humans: A Case for Dual Entrainment in the Treatment of Alzheimer's Disease

Mariana G. Figueiro^1,2* and Sagan Leggett^2,3

• ¹Department of Population Health Science and Policy, Icahn School of Medicine at Mount Sinai, New York, NY, United States
• ²Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, United States
• ³Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY, United States

Circadian sleep disorders are common among American adults and can become especially acute among older adults, especially those living with Alzheimer's disease (AD) and mild cognitive impairment (MCI), leading to the exacerbation of symptoms and contributing to the development and advancement of the diseases. This review explores the connections between circadian sleep disorders, cognition, and neurodegenerative disease, offering insights on rapidly developing therapeutic interventions employing intermittent light stimuli for improving sleep and cognition in persons with AD and MCI. Light therapy has the potential to affect sleep and cognition via at least two pathways: (1) a regular and robust light-dark pattern reaching the retina that promotes circadian phase shifting, which can promote entrainment and (2) 40 Hz flickering light that promotes gamma-wave entrainment. While this is a new area of research, preliminary evidence shows the potential of dual circadian and gamma-wave entrainment as an important therapy not only for those with AD, but for others with cognitive impairment.

Introduction

Forty-five percent of Americans report sleep problems that affect their daily activities at least once per week, with 35% reporting poor or fair sleep quality and 20% reporting that they did not feel refreshed by sleep on any day of the past week (1, 2). Asynchrony between normal work and social schedules and the timing of the internal clock (3) can lead to sleep disorders and sleep deprivation, particularly if the asynchrony is prolonged for an extended period, which in turn can negatively affect task performance, cognition, and general health (4–6). Sleep disorders and their attendant decrements can become especially acute among older adults, especially those living with Alzheimer's disease (AD) and mild cognitive impairment (MCI), leading to the exacerbation of symptoms and contributing to the development and advancement of the diseases (7–9). In fact, of the estimated 5.8 million people in the United States living with AD and related dementias (ADRD) (10), at least one-third experience difficulty sleeping (11, 12) and approximately two-thirds of their estimated 18.5 million unpaid caregivers report sleep disturbances themselves (10, 13, 14).

This review explores the connections between circadian sleep disorders, cognition, and neurodegenerative disease, offering insights on rapidly developing therapeutic interventions employing entraining light stimuli (both continuous and intermittent) for the treatment of sleep disorders, including in those with AD and MCI. Light therapy has the potential to affect sleep and cognition via at least two pathways: (1) a regular and robust light-dark pattern reaching the retina that promotes circadian phase shifting and thus, entrainment and (2) 40 Hz flickering light that promotes gamma wave entrainment. Both are discussed below.

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