Reclaiming Gamma: CRT Flicker, Natural Rhythms, and 40Hz Therapeutics in the Context of Dementia

Abstract:
As rates of dementia and Alzheimer’s disease rise globally, researchers have begun investigating 40Hz auditory and photic stimulation as a promising non-invasive therapy. This paper explores an underexamined question: did humans historically receive passive 40Hz gamma-frequency stimulation through now-abandoned environmental or technological means, such as cathode ray tube (CRT) televisions or immersive natural experiences?

Drawing from neuroscience, environmental psychology, and media history, we explore whether our sensory environments prior to digital screens may have contributed to cognitive resilience via subconscious gamma stimulation. This cross-disciplinary analysis aims to reframe modern 40Hz therapeutics not as novel inventions, but as attempts to reclaim lost rhythms of the environment and technology.

1. Introduction
Alzheimer’s disease and dementia are among the most pressing public health challenges of the 21st century. With an aging global population and no definitive cure, researchers have increasingly turned to non-invasive stimulation therapies. A particularly promising candidate is 40Hz light and sound stimulation, which has been shown in animal and early human studies to entrain gamma brainwave activity, reduce amyloid plaques, and improve cognitive function. However, few have asked: did our ancestors, or even citizens of the analog era, already receive such stimulation naturally or incidentally?

2. The Rise of 40Hz Therapy
The resurgence of interest in gamma entrainment began with a 2016 MIT study demonstrating that 40Hz light flicker reduced Alzheimer’s pathology in mice. Since then, research has expanded to include 40Hz auditory stimulation, combined sensory input, and wearable or in-home devices designed to stimulate the brain with gamma-frequency rhythms. These devices aim to restore a form of neuronal synchronization often lost in aging and dementia.

3. CRT Television Flicker and Ambient Gamma Exposure
Prior to the digital revolution, most households relied on CRT monitors and TVs, which operated at refresh rates between 50 and 60Hz, with some effective flicker frequencies perceived at lower rates due to interlacing and phosphor decay. Anecdotal and observational data suggest that these devices often emitted flicker within or near the gamma frequency band (30–50Hz). Though unintentional, this passive visual stimulation occurred daily for millions of people, often for hours at a time. While there is no direct evidence linking CRT exposure to reduced dementia, the timing of CRT obsolescence in the 2000s loosely correlates with the accelerating rise in Alzheimer’s diagnoses.

4. Nature, Rhythm, and Sensory Stimulation
Natural environments, particularly forests, oceans, and fire-lit settings, are rich in sensory rhythms that may stimulate the brain. Although flickering light in nature (e.g., through leaves or firelight) typically operates below the gamma band (e.g., alpha or theta ranges), deep immersion in multisensory natural spaces has been linked to improvements in attention, working memory, and neuroplasticity. Furthermore, meditative and flow states often seen in nature-based experiences are associated with endogenous gamma activity. In this sense, time spent in nature may support gamma synchronization through internal rather than external rhythmicity.

5. Flicker-Free Modern Life and the Loss of Environmental Gamma
Modern lighting, LED screens, and environmental design prioritize visual comfort by eliminating perceptible flicker. While this reduces eyestrain, it also removes incidental gamma-band stimulation once provided by analog technologies. Combined with increased screen time, indoor confinement, and digital overstimulation, today’s environments may suppress gamma synchrony, contributing to cognitive decline.

6. Therapeutic Reclamation of Gamma Rhythms
40Hz light and sound therapy can be understood as a technological attempt to restore a brain rhythm previously supported by the environment and older media technologies. Devices like 40Hz light panels, gamma headphones, and wearable stimulation patches deliver targeted gamma-band input to the auditory and visual cortex. Emerging results suggest these tools may slow cognitive decline, reduce neuroinflammation, and improve quality of life.

7. Implications for Future Research and Design
If passive gamma stimulation once occurred through CRT technology and immersive natural experiences, future neurotechnology should consider reintegrating these rhythms into daily life. This may include gamma-enriched lighting, ambient flicker therapy, or devices that merge biophilic design with cognitive stimulation. Cross-disciplinary research bridging neuroscience, media ecology, and environmental psychology is needed to explore the long-term cognitive effects of our sensory environments.

8. Conclusion
While speculative, the connection between historical ambient gamma exposure (via CRTs and nature) and today’s therapeutic use of 40Hz stimulation raises important questions. Have we unknowingly eliminated beneficial brainwave stimuli from our daily lives? Could non-invasive gamma entrainment restore what the digital world has erased? As 40Hz therapy continues to show promise, examining its roots in forgotten rhythms may shape a more neurologically harmonious future.

References:

• Iaccarino et al. (2016). Gamma frequency entrainment attenuates amyloid load in Alzheimer’s disease models. Nature.
• Lutz et al. (2004). Long-term meditators self-induce high-amplitude gamma synchrony. PNAS.
• Alzheimer’s Association (2025). Facts and Figures.
• MIT Picower Institute. (2022). 40Hz Sensory Stimulation and Alzheimer’s.
• Frontiers in Neuroscience (2023). Gamma entrainment and cognitive outcomes.
• Environmental Psychology journals on nature-based cognitive restoration.