First of all, thanks for the answers...

I have CO2 from a chemical reactor (HCl + NaHCO3) running the whole time - I'm too lazy to regulate the flow every morning and the power head I use to dissipate it in the water doesn't work if it gets too much air inside, so I can't plug it to a timer. Also, no direct sunlight at all.

Sorry if I wasn't clear. I meant nonstop as a really long period of time, like 24 hours or more, and not just 10 hours nonstop.

As an exemple, if you interrupt the photoperiod (I don't know how long or what drop in intensity it would take), dividing it in two, the plant may interpret it as if the days have gotten shorter.

I was wondering if the intensity of the room's ilumination would be interpreted by the plants as photoperiod, so my plants would be exposed to a photoperiod of lets say 15 hours (8:00 AM to 23:00 PM), not fully using the final hours of light... I don't know if I was clear enough...

Regards,
Bode.