Some individuals are more sensitive to light at night, which can shift their circadian clock and cause wakefulness.

“there is some evidence that People's Light sensitivity particularly the iprgc or this intrinsically photosensitive retinal ganglion cell or the simple speakers the blue light sensors in our eyes — there seems to be even one log unit change in sensitivity as measured by pupil constriction so for some people a small amount of artificial light at night could really shift their circadian clock yeah wake them up essentially and then for some it manner”