Preliminary results on the infl uence of workplace lighting on transitory mood and subjective sleepiness

TONELLO, G.; HERNÁNDEZ N.E.; LÓPEZ ZIGARÁN, S.

LUND

Conferencia; THE HUMAN BEING AT HOME, WORK AND LEISURE. Sustainable use and development of indoor and outdoor spaces in late modern everyday life; 2016

Lund University, Sweden

Preliminary results on the infl uence of workplace lighting on transitory mood andsubjective sleepinessGraciela Tonello1, Nancy Hernandez de Borsetti2, Santiago López Zigarán11Universidad Nacional de Tucumán / CONICET, Argentina; 2Instituto de estudios CelularesLight aff ects human lives in several ways. The visual eff ects of lighting are related to visualperformance, while the non-visual or psycho-biological eff ects involve health and wellbeing.Their action spectrum curves are also diff erent; the visual peak effi ciency lies inthe yellow-green wavelength region while the maximum biological sensitivity lies in theblue region of the spectrum. Thus, lighting designers can use the color of light as well asits level to provoke psychological and physiological states such as alertness or relaxationwhen needed. In this regard, the spatial distribution of light is also important since there isa denser distribution of melanopsin, the circadian photoreceptor, in the inferior part of theretina, which makes an important diff erence between light reaching the eye from abovethan from below.Preliminary data from a simulated laboratory experiment where the investigation of theinfl uence of level, color and spatial distribution of light on transitory mood and sleepinessof offi ce workers are presented. The aim was to identify the lighting conditions that favorproductivity without deteriorating wellbeing. The subjective sleepiness was assessed by theEpworth Sleepiness Scale and the transitory mood by the Scale for Mood Assessment.The laboratory setup consisted of two offi ce workplaces separated by a wood panel, litwith diff erent color temperature lamps (3000/4000K). Two lighting levels were provided bya general lighting from compact fl uorescent lamps (Eh 500 lx, Ev 200 lx) and the other byadding a wall washer lighting from leds tubes on the front wall (Eh 800 lx; Ev 900 lx). Theseconditions were randomly administered and each of the four lasted 1,5h.The analyses were performed on 76 evaluations. The outcomes of two groups werecompared based on 20 assessments carried out on a printed format and the other on acomputer screen.Based on the computation of three indices of subjective sleepiness, transitory mood andperception of lighting, the results show that the highest mood was reached under the warmlight-higher level, while the lowest occurred with cool light-lower level.The chance of dozing during the experiment was higher in the cool light-lower level and lessin the warm- lower level. The mean values for warm and cool lighting both with the higherlevel were similar. No statistically signifi cant diff erences between the two groups werefound for mood nor sleepiness.The appraisal of the lit space as well as the visibility conditions were better evaluated under the warm light-higher level, and statistically signifi cant diff erences were found between thegroups, being better on the printed assessment test. Nevertheless, more visual symptomswere reported by this group. The highest number of symptoms occurred under the coollight-higher level.In conclusion, the results show that the color of light is important for transitory mood, andthe lighting level for alerting eff ects. A preference for warm lighting with higher level wasdisplayed.