how long of light duration for the tank?

[ole]

i got neon tetra, yamato shirmp, otto, java moss, emerse water spirte and alternanthera sp in a small 5G tank.

i'm wondering how long of duration is too much or too little for the tank.

i put my tank in my room whereby during bright daylight time, i'll need to turn on the lights for reading. pretty low intense daylight.

i'm wondering if its okay to turn on the lights while i'm home and awake (5pm till perhaps 2-3am.) will a short period of 4-5hours of complete darkness be okay for the tank? will too long of light duration stress the system?

and since my room receives poor daylight, what's the minimum duration of proper lighting i need to give for them to grow well?

[ole]

oh yeah, is it okay to keep turn on and off the light. like i will come into my room, want to see fish, so i turn light on. after a while i going out so i turn it off. 2hrs later i come back, i turn the light on again. then maybe turn light off again when i go to my bed for reading then my niece come in after a while and i turn the light on again to let her see fish.

will the constant change of lighting stress the fish/shrimps on the long run?