The akaris mask recreates the horizon – and promises relaxation and fitness in just fifteen minutes.

Jens Balasus, one of the two founders of akaris, hands me what looks like a pair of ski goggles. Although we are sitting in a well-lit office, my eyes first have to adjust to the dazzling daylight behind the mask. A sunny sky arches above me – the effect is similar to wearing a VR headset. The sun is just rising, or at least that is what the scene displayed in the goggles imitates. Gradually, a blue summer sky begins to shine. “When you’re lying on your back, it’s like lying on the grass and gazing into the distance,” explains akaris co-founder Alexander Herzog.

This sense of wellbeing has a scientific basis, the two founders explain: “At the Department of Adaptive Lighting Systems and Visual Processing, we also research the health-related components of light.” Like all living beings, humans are strongly oriented towards a day–night rhythm, as shown by performance curves and our need for sleep at night. The key regulator is daylight, which governs our activity cycles through the body’s own hormones such as melatonin and serotonin, influencing numerous biochemical processes. “Yet we spend 90 per cent of our time indoors, where natural light can hardly regulate our internal clock,” says Herzog.

Even modern indoor lighting emits only parts of the solar spectrum, the lighting engineers point out. To create lighting similar to daylight, it is necessary not only to combine many specific wavelengths but also to achieve a defined illuminance – that is, the amount of light falling on a surface. For more than seventy years, the Department of Adaptive Lighting Systems and Visual Processing at TU Darmstadt has been researching the interdisciplinary effects of light on human health, including harmful influences such as UV radiation. “The positive effects of light on our bodies tend to become noticeable over the long term – and they are surprisingly underused,” says Herzog. The two scientists, who worked at neighbouring desks in the department, decided to change that.

The impression of a horizon and distance allows the eyes to relax. “We simulate sunrise and sunset right through to a blue sky,” Balasus explains, describing the changes in the visual display. Herzog sketches the wavelengths of conventional LED luminaires, which reveal a significant gap in the spectrum: “This spectral gap can be detrimental to the human internal clock in winter.”

Thanks to their specialist knowledge, they are able to reproduce the daylight spectrum precisely within the visible range using the mask – without harmful UV radiation or blue-light damage. The next model is more compact and features a more refined design. Since the beginning of the year, product designer Erika Martinez Duque has been supporting the team. The next goal is the production of a modern lifestyle wearable.

Together with HIGHEST, they applied last year for an EXIST start-up grant – successfully. Since November 2025, their three positions have been funded, along with material resources and coaching. One advantage of the EXIST programme is its contractual link to TU Darmstadt. The head of the department, Tran Quoc Khanh, enables akaris to use laboratory facilities and supports them with studies.

They recently applied for a patent for the akaris mask technology. Users do not see a uniformly illuminated surface – “that would feel like dense fog or a snowstorm, with no sense of orientation,” Herzog explains – but rather a structured “sky” with a sense of depth. This effect is created by specially arranged and selected light sources with corresponding optics. With a bright white mask and a uniform background, the eyes would constantly strain to find a point of reference or pattern.

The founders see strong demand for the light mask in the lifestyle sector, particularly for performance enhancement, sleep optimisation and improving mood and energy during winter. Following feedback on the prototype, marketing is now the focus. For follow-on financing, akaris is currently reviewing various options. “We want to be able to make a living from this,” the inventors say confidently.

The mask will be sold via a web shop – potentially in partnership with companies in the wellness and sports sectors – to reach a broad target audience. Beyond fitness applications, the benefits for people who have to cope with irregular working hours will also be a priority. “And people in care homes often suffer from sleep and rhythm disorders due to insufficient direct daylight,” says Balasus. Further studies in collaboration with TU Darmstadt are planned to explore additional applications.

Akaris expects particularly strong demand from people affected by the winter blues, which up to a fifth of the population report, especially in northern regions. Expansion into Scandinavia is therefore on the agenda. An accompanying app will be available, offering visual experiences such as “sunrise in Egypt” or breathing exercises combined with meditation. “We want to make the positive aspects of light accessible,” says Balasus. “In the long term, we aim to become the leading company for light-based interventions,” Herzog describes their ambitious vision. Akaris intends not merely to track vital data, as conventional fitness watches do, but to influence and optimise sleep, performance and wellbeing in a targeted way.

As I leave the – well-lit – office after our conversation, the winter sun under a blue sky lifts my spirits: in its natural form, this mood enhancer is already remarkably effective.