Cognitive claims deserve the most scepticism of any category in wellness, because they are the hardest to measure and the easiest to feel. Mental clarity is subjective, fluctuates with sleep and stress, and improves for a dozen reasons unrelated to whatever was tried last week. That is exactly why the randomized literature matters here more than testimony.
What the Cognitive Research Reports
The most relevant recent work is a 2025 systematic review and meta-analysis of photobiomodulation effects on cognitive function. Drawing on randomized controlled trials, it reported potential benefits on specific cognitive measures while stressing two limitations: protocols varied widely between studies, and the quality of the underlying evidence needs to improve before firm conclusions are possible.
The 2025 umbrella review of photobiomodulation — 15 meta-analyses, 204 randomized controlled trials, more than 9,000 participants — is the wider frame. Cognitive function appeared among the outcomes with moderate-certainty evidence, which puts it at the stronger end of a field where most outcomes rested on low or very low certainty and none reached high certainty.
Transcranial Delivery and Its Open Questions
Cognitive PBM research usually involves transcranial delivery — light applied to the head with the intention of reaching cortical tissue. A 2025 systematic review on enhancing sleep, wakefulness and cognition with transcranial photobiomodulation discussed possible relationships involving cerebral mitochondrial activity and cerebral blood flow.
The unresolved question is dosimetry. How much light of a given wavelength actually reaches cortical tissue through scalp, skull and cerebrospinal fluid, and how much is needed there to matter? Until that is standardized, trials using different devices are not really testing the same intervention — which is precisely the heterogeneity the meta-analyses keep flagging.
Where The Light System™ Sits
The Light System™ is a proprietary light-based wellness technology whose published research reports bioelectrical activity and cellular conductivity measurements — including up to 80% increased conductivity following TLS Chair exposure. Those are laboratory readings, not cognitive endpoints. No conductivity figure, of any size, demonstrates improved attention, memory or executive function in a person.
So the accurate statement is layered. Photobiomodulation research suggests possible cognitive effects under specific tested conditions. TLS has not published equivalent randomized cognitive trials. Anyone exploring TLS for mental clarity is exploring a plausible wellness objective, not a validated cognitive intervention — and the company's own handbook states that it makes no medical claims about the technology.
What Reliably Affects Cognition
Anyone genuinely interested in mental clarity should get the unglamorous inputs right first, because their evidence base dwarfs anything in the light literature: consistent sleep, aerobic activity, nutrition, alcohol reduction, stress load, and treatment of any underlying condition. Light exposure, if it helps, helps at the margin of those foundations. Marginal gains are worth having — but only once the foundation is in place.
For clinical context on how we approach cognitive and mood-related concerns under physician supervision, see depression treatment, hyperbaric oxygen therapy, and the full Light System™ research guide. You can also compare photobiomodulation versus TLS.
Educational information only. Not medical advice, not a diagnosis, and not an offer of The Light System™ as a service at Sanctuary Tulum.