Cannabis is a C3 plant, meaning they can intake carbon dioxide at all times do not require a dark period to respire and carry out other necessary life functions. Photoperiods require 12/12 lighting to induce flowering, but do not require a dark period to carry out necessary life functions. When cannabis plants are in light they conduct photosynthesis to produce NADPH and ATP. These products are then used in the Calvin cycle to produce carbohydrates. The Calvin cycle is light independent so it doesn’t need light to occur, but it also doesn’t need dark to occur either. Since an autoflower is not light dependent to flower you can run lights 24/0. Many growers and breeders do this with no ill effects. Some growers believe the plants need a rest period to grow properly and the auto flower community is split on this subject but as far as I know the science science surrounding these plants show they do not need a lights off period. We really need a peer reviewed study comparing different light cycles to say anything otherwise