If You Must Have A Night Light, Let It Be Red
Sleep challenges are becoming more and more common these days. One of the known reasons for this is that we are exposed to so much light right up until the time we turn off the lights and try to go to sleep that our pineal gland is not producing melatonin in time for us to get sleepy naturally. The usual pattern before electricity and artificial lights was that when the sun went down, our melatonin levels would rise, peaking in the middle of the night and making us sleep well. Night lights have been shown to reduce melatonin further and thus making sleep problems even worse. Poor sleep has been associated with depression and mood disorders.
The study (read it here) outlined by Science daily, shows that white lights and blue lights were far worse than red lights in causing depression symptoms. This study was in hamsters, so at least if you are a hamster, I would recommend using a red light for the night light. It might be a good idea if you must have a night light, that you consider trying a dim red light for that purpose. No night light at all is best.