Your bedside lamp should give off a warm and glowing shade of white with a yellow tint, bringing coziness to your bedside table. At least, the light should be at 2700K.
This is indicative of the temperature at which the bulb starts emitting light and mimics candlelight. Subconsciously, this lower, warmer light helps you brain recognize that it's time to wind down, and why you should keep your phone out of arm's reach too!
You can go up to 3000K but this is slightly more of a pure white color and you might want to avoid anything too bright to avoid glare in your bedroom.