Figure 2.

(a) Lighting levels representative of typical lighting exposure in the modern era. Light intensity levels of typical activities (watching TV, laptop use) were measured using a BH1750 Digital Light Sensor with an artificial light on (average value 100 lux) and off (average value 40 lux), respectively; (b) experienced social jet-lag in modern society, quantified as the time difference between the unconstrained sleep and wake-up times (blue bars) and sleeping and waking up under the constrains of working times (orange bar).