## 1 Introduction  
Circadian rhythms are likely the evolutionary result of increased fitness when following the natural light and dark day cycle. In humans, circadian rhythms shape rest and activity patterns through nychhthermal changes in specific hormone levels, neuronal activity, and body temperature [1]. Through artificial light at night (LAN), the practical necessity to closely follow the natural cycle has waned in recent generations. The departure has been most prominent in shift and especially night shift workers, a group that suffers from severe detriments of their physiological and psychological health [2]. Here, we propose one exemplary solution for artificial lighting in an industrial production facility to help alleviate these negative effects, alongside an easy-to-use method for the nonvisual lighting design. Long-term night shift workers have an increased risk of suffering from poor sleep and neurological disorders [2; 3] and cardiovascular and metabolic diseases [4], and they are possibly more vulnerable to certain types of cancer [5]. All of this is not simply the result of a circadian phase change toward nightly activity. Rather, the aberrant patterns, such as between work and social life or changing shifts, prevent a stable rhythm [6]. Biological processes that otherwise occur at the \"right\" internal time, such as immune reactions, DNAreplication, and food processing, are then reduced or susceptible to harmful changes. The negative effects of shift work stated above are thought to be a direct effect of this affliction, called chronodisruption [6]. Minimizing chronodisruption is thus one major goal when creating a work environment for shift workers. The internal biological clock, located in the hypothalamic suprachiasmatic nucleus (SCN), can adjust to changes in phase over time and, to some extent, to the period [7]. The main Zeitgeber (time giver) to the SCN is light [8], although physical activity, social cues, and, possibly, food intake also set the internal clock. Information about (day)light status reaches the SCN through the retinoblastoma tract, with _intrinsically photosensitive retinal ganglion cells_ (ipRGCs) serving as the main light receptor [9; 10]. These photoreceptors contain the pigment melanopsin and have a peak wavelength sensitivity of about 480 nm at the retinal level or about 490 nm at the corneal level for a 32-year-old standard observer [11]. IpRGCs have a high sensitivity threshold compared to rods and cones [12], and ipRGCs in the inferior retinal half seem to be more sensitive compared to those in the superior half [13]. Light responses that originate in or are mediated by ipRGCs are called nonvisual or non-image-forming (NIF) effects of light. Relevant NIF effects for night shift work are the suppression of the sleep hormone melatonin [14] and acute alertness [15; 16] through ipRGC stimulation, as are circadian phase shift [17] and circadian amplitude attenuation [18]. Managing these effects through artificial lighting by inducing a stable rhythm might go a long way toward reduced chronodisruption in shift workers. At present, there are only tentative recommendations on what the \"right\" light for shift workers is [19; 20], and there may never be a conclusive one due to the complexity of differing requirements. However, with (night) shift work as a major part of the job market [21], working toward \"better\" lighting is a necessity. It is also clear that any lighting design must strike a balance between visual requirements and the aforementioned NIF effects, as well as emotional aspects--a concept which the CIE termed as _integrative lighting_[22]. In 2018, we were tasked with the design and evaluation of an artificial lighting system for a shift workspace in an industrial production facility in Bavaria, Germany. The lighting design should incorporate the current knowledge of nonvisual effects in the context of (night) shift work and should be adaptable to other workspaces.