Question about flight levels

Do commercial jets fly at lower flight levels at night? May sound like a dumb question, but I could swear that as I look up in the day planes seem to fly higher than at night. Maybe it is cause the lights at night make the planes seem closer, but I could swear the planes are closer at night. Is this an optical illusion or are my observations right?
I'm no jet pilot, but I'm 99.999% certain they don't fly noticably lower at night (taking into account the temperature difference at night). Sounds to me like it's just an illusion caused by the bright aircraft lighting.
Actually, light reflected off an object gives it the illusion of being at a further distance.

Direct light looks much closer because of a lack of distortion.

Compare trying to turn left on the road at night, compared to the middle of the day.