People that were exposed to 100 lux of light during sleep for one night had higher markers of insulin resistance (such as higher insulin levels) compared to individuals that were not exposed to light during sleep.
The light exposure likely disrupts sleep and leads to poor sleep. Other clinical trials have shown that poor sleep (4 hours a night for 2 nights) can result in 20% higher circulating insulin levels.
100 lux is similar to a dim family room light and is quite a bit of light to be exposed to during sleep hours. 5 lux is similar to a street light from outside lighting up a room at night and has also been adversely linked to health.