Check bedroom darkness for sleep.
Melatonin production is suppressed by surprisingly little light, and the practical target for a bedroom is around one lux — dark enough that you cannot read by it. Standby LEDs contribute a few tenths of a lux each and an uncovered streetlight contributes several, so the estimate takes the higher of your measurement and the sum of those known sources. The score turns that into a single number you can improve source by source.
Bedroom darkness
Estimated lux = max(measured lux, LEDs x 0.4 + streetlight contribution); darkness score = 100 - estimated lux x 8, floored at 0
These figures are estimates based on population-average formulas and are intended for training and recreational planning only. They are not medical advice. Consult a qualified health professional before starting or changing an exercise programme, particularly if you have an existing medical condition.
As close to complete darkness as practical — around one lux or less. If you can make out object detail after a few minutes, it is brighter than ideal.
Individually they are weak, but blue and green indicators are disproportionately effective at suppressing melatonin. Covering them is cheap and measurable.
A well-fitted mask blocks more light for less money; blackout curtains keep the whole room dark, which matters if you wake and move around.