Jumping right to the conclusion, if you have LED lights, don’t go out of your way to turn them off (except as the last thing at night).
I have always been a habitual light-turner-off person. If I pass through a room with a light on and nobody is there, I will turn off the light. This is my dharma, the way my momma raised me. But LED lights today take so little electricity, it is hardly worth the effort, especially at my age when the distraction is enough for me to forget where I was going in the first place. Often,the light gets turned off, but the more important thing I was expecting to do gets forgotten.
I realized the incongruity when I was planning to add a timer to my outdoor LED post light to turn it off during the day. The light only took 3 watts, but the timer would consume 5 watts and run continuously. Better I should leave the light on, day and night.
Like many others, I initially replaced my old incandescent lights with those curlicue CRL florescent lights, but they took about 30 seconds to come to full brightness and many of the initial ones were “cool white.” My living room was lit like an all-night supermarket. And 30 seconds is a long wait when you are trying to read something. I have been slowly replacing them with LEDs.
LED lights are still sold by the wattage of their familiar incandescent equivalent, such as “60 watt replacement,” but eventually we will learn to go by lumens, which is the actual output of light. But now we have to also consider the warmth, which is the relative amount of red to blue, that varies from product to product.
The designation “warm” or “cool” is only an imprecise psychological designation. A more accurate designation in degrees Kelvin is now common.
Lord Kelvin, back in the 19th Century, measured the temperatures of a heated block of black carbon. At low temperatures, it glowed a dull red, but eventually it turned white hot at high temperatures. (He also did far more important things and had an entire temperature scale named for him.) For comparison, the temperature of a standard incandescent light is 2,700 K and a cool white florescent shop light is about 5,000 K. TV screens can be over 9,000 K, which is why they look so blue when seen from outdoors. It’s all what appeals to you, and now you get to chose.
(Camera film used to come in two forms: indoor and outdoor. If you mistakenly used the common outdoor film indoors under incandescent light, everything in the prints looked red. Digital cameras today will accurately set the “white balance.”)