Research – HumanCharger

HumanCharger® Research

"The human brain, per se, is sensitive to light"

This hypothesis was the starting point of Valkee's scientific research, in cooperation with Research Team from the University of Oulu, Finland, in 2007.

The studies, all placebo-controlled, conducted since mid-2012, focused on the responses and applications of transcranial bright light (TBL).

Between 2008-2010, Researchers at the University of Oulu , Finland, discovered that in addition to eyes, areas of the human brain are also sensitive to light. This sensitivity is due to the photoreceptor-proteins in the brain, which are similar to those found in the eyes, a discovery that had been made by researchers in the U.K. and the U.S. 10 years earlier. University of Oulu researchers found that brain areas can be reached by light through ear canals, ear tissues and bone skull. The Skull of large mammals, including humans, lets light pass through naturally. In ordinary daylight and daytime conditions the brain is constantly being exposed to light.

brain1    brain

Valkee Science Overview and Publications

Please find below a summary of the science behind the HumanCharger®. For more information please download the science summary.

The human brain is inherently sensitive to light

University of Oulu, Finland:

In all areas studied, the research located the protein encephalopsin (OPN3), a photosensitive receptor found in brains of both humans and mice. These receptors include the core areas of serotonin, dopamine production and storage and noradrenalin, which play key roles in regulation.

PDF: Encephalopsin (OPN3) protein abundance in the adult mouse brain.

University of Tampere, Finland:

This study demonstrates that extraocular light affects human brain functioning. Extraocular light modulated attention-related brain responses, specifically pertaining to emotion-attention interaction. The study confirms that light is capable of penetrating the human skull via ear canals and reach the temporal lobe of the brain. Because the brain floats in cerebrospinal fluid, transmitted light might be widely dispersed, thus illuminating the basal surface of the temporal lobe. Penetration of light through ear canals was investigated on a human cadaver after the brain was removed upon autopsy. Light penetration of the skull was visible with surgical lights on or off. Light was able to reach intracranial space through the ear canals and was visible at the base of the skull under the temporal lobes.

PDF: Human brain reacts to transcranial extraocular light.

Earlight activates neural networks of the human brain

Bright light via the ear canal causes a biological response in the human brain neural networks as seen in the placebo-controlled, single blind, functional magnetic resonance imaging study, suggesting that the brain tissue is inherently light-sensitive. In the study conducted by the University of Oulu researchers, the human brain’s visual and sensomotor cortexes showed significant increased functional connectivity in the light group as compared to the placebo group.

PDF: Stimulating brain tissue with bright light alters functional connectivity in brain at the resting state.

Earlight improves cognitive performance

Valkee’s placebo-controlled clinical study conducted on top athletes

Psychomotor speed tests with visual warning signals were administered to a Finnish National Ice Hockey League team before and after 24 days of transcranial bright light (TBL) or placebo treatment. A daily 12-minute dose of bright light or placebo (n = 11 for both) treatment was administered every morning between 8–12 am at home with a transcranial bright light device. Motor time with a visual warning signal decreased in the bright light treatment group but did not change significantly in the placebo group. There was a statistically significant difference between the groups in decrease of motor time.

PDF: Effects of bright light treatment on psychomotor speed in athletes.

The effects of earlight are not mediated via melatonin

Eight healthy young adults participated in placebo controlled crossover trial. The subjects were exposed in random order to 24 minutes of transcranial bright light (TBL) or placebo exposure via ear canals at 01:10 h. The saliva and urine samples for melatonin and cortisol measurements were collected hourly between 9-3am and at 6-9am, at 12pm and 6pm. There were no significant differences in the melatonin or cortisol concentrations between the exposures at any sampling points. The curves of melatonin and cortisol secretion concerning the circadian surges and acrophases paralleled those profiles seen under controlled conditions. The present results indicate that TBL via ear canals does not suppress nocturnal melatonin secretion.

PDF: Transcranial bright light exposure via ear canals does not suppress nocturnal melatonin in healthy adults -a single blind sham-controlled crossover trial.

Transcranial bright light alleviates jet lag symptoms.

This randomized, double-blind, placebo-controlled field study demonstrates that intermittent transcranial bright light exposure via ear canals alleviates jet lag symptoms. A total 55 healthy male subjects completed the study. Subjects were required to travel by plane from Finland (time zone: +2) to North America (time zone: -5 to -8) and stay a minimum of one week in their destination time zone. During the post-travel period, subjects were exposed to TBL or placebo treatment four times per day 12 minutes each at predetermined times. TBL or placebo exposures were administered every 2 hours between 8am to 2pm on travel day 0 and every 2 hours between 10am to 4pm on post-travel days 1-6. The subjects were randomly assigned to the bright light treatment (N=25) group or the placebo (N=30) group. The study set-up for the placebo group was the same with the exception that the bright light device was inactive. The effect of TBL on jet lag symptoms was measured after traveling eastwards. Symptoms of jet lag were measured by the Visual Analog Scale (VAS), the Karolinska Sleepiness Scale (KSS), and the Profile of Mood States (POMS). There were a significant reduction of overall jet lag symptoms, subjective sleepiness, fatigue, inertia and forgetfulness when comparing the TBL group (N=25) to the placebo group (N=30).

PDF: Transcranial bright light and symptoms of jet lag a-randomized place-controlled trial.

Transcranial bright light alleviates winter blues symptoms

Valkee clinical, double-blinded study with 89 SAD patients

During this four week study, 89 subjects suffering from SAD were randomized to receive a 12-minute daily dose of photic energy of three different intensities (1 lumen, 4 lumens or 9 lumens) at home. The response rates (at least 50% reduction) varied between 74-79% for depression (BDI) and 47-62% for anxiety (HAMA) symptoms. There were no intensity based (1 lumen, 4 lumens or 9 lumens) dose response relationships in the improvement of anxiety and depressive symptoms or cognitive performance between treatment groups receiving different intensity of bright light via ear canals.

PDF: Transcranial bright light treatment via ear canals in seasonal affective disorder: a randomized controlled double-blind dose-response study.

Here are the rest of studies:

PDF: Transcranial light affects plasma monoamine levels and expression of brain encephalopsin in the mouse.

PDF: Altered resting state activity in seasonal affective disorder.

PDF: Can transcranial brain targeted bright light treatment via ear canals be effective in relieving symptoms in seasonal affective disorder? A pilot study.

PDF: Group-ICA model order highlights patterns of functional brain connectivity.

Have more questions? Simply contact us and we will provide the answers.

Сontact us with any questions that you have!