Light: plenty by day, almost none at night

By day a room usually has 300–500 lux against a hundred thousand outside. In the evening 200 is enough to shift sleep. The device sees both.

Which numbers are normal

The zones on the device screen. Colour appears only where attention is needed.

150 lux and up by day	enough
50–150	attention
below 50 by day	dark
at night	no colour: darkness is the norm for sleep

SanPiN 1.2.3685-21 table 5.52 = SP 52.13330: living rooms 150 lux, children's rooms 200, workplaces 300

Real frames from the device, captured on 4 September 2026.

Ordinary room light in the evening, under 200 lux, delays melatonin onset in almost everyone and shortens its night by about an hour and a half.
Even 30 lux from a phone screen at eye level noticeably shifts the melatonin peak.
Just 5 lux in the bedroom at night almost doubled the risk of depression in a large Japanese cohort.
By day, on the contrary, there is too little light: the daytime recommendation is 250 melanopic lux and up at eye level, up to 10 in the evening, up to 1 at night.

Gooley et al. JCEM 2011; Obayashi et al. HEIJO-KYO; Brown et al. PLOS Biology 2022

Hints in words on the screen. Actions about the room, not about the body.

“Dim the lights” — in the evening, a couple of hours before bed.
The device dims its own screen too: by the light sensor, and never above 15 % at night.
“Too dim to work” — below 150 lux on the desk by day.

Which way does the sensor face?
Backwards, at the wall. It catches reflected light, so the device is best placed near a light wall rather than facing a dark corner.