As I'm not in your grow room, I can't be 100% sure. What I do know is that classic leaf drooping is a symptom of water stress - either underwatering or overwatering.
Leaves also droop during the dark period when they are not photosynthesising.
And then there is the plant's response to stimuli - leaves following a light source (either "standing up" to reach an overhead light, or turning towards a side-on light).
Underwatering is easy to tell, as the leaves not only droop, but appear paper-thin. This is because there is less water in the plant, so there is less hydraulic (hydrostatic) pressure in the stems (which cause the leaves to droop), while the leaves themselves will feel thinner because there is less water in the cell membranes.
Overwatering shows similar symptoms, but the leaves are normal thickness, or slightly thicker, as they have plenty of water in the cell membranes, which weigh the leaves down (normal water transfer inside the plant can't happen because the roots are starved of oxygen and not functioning properly as they begin to die off). The plant becomes "waterlogged" - for want of a better term.
Plants droop during the dark period because they are not photosynthesising - they are respiring. During photosynthesis, plants convert sunlight into sugars using water and carbon dioxide. During the dark period, they use oxygen to convert those sugars into energy. Photosynthesis, therefore, requires light - which is why the leaves turn towards any light source (obviously) - and water - which is why the leaves are "perky", because there is a lot of hydrostatic pressure, or water movement, inside the plant.
During the dark period, there is less hydrostatic pressure (no photosynthesis), and so the leaves "droop" - this is perfectly normal. It is reasoned that most plants also "droop" at night because water (moisture/humidity/rain etc) drips off the leaves and prevents mold and other pathogens from taking hold.
Which brings us back to your particular "drooping" leaves. As I said earlier, if your plants "droop" when the light is next to them, yet point upwards when you raise the light, then this indicates they are healthy and simply following light-sourced stimuli to better photosynthesise.
Apart from a bit of leaf-tip stress, your plants look healthy to me - no signs of water stress - so in my opinion, my first explanation is the most likely.