GMO plants, like all other plants, do not “sleep” in the sense that you and I as mammals sleep. However, plants do have natural processes that may be cyclic or seasonal, indicating a cycle or rhythm to their growth and life. This is not technically “sleeping” but let me give you a couple of examples of what I mean.
Some plants have a type of metabolism known as CAM (Crassulacean Acid Metabolism). Plants which have CAM close the pores on their leaves to limit water loss during the day and at night, open the pores open to admit carbon dioxide. The carbon is stored at night, and then during the day it is used for photosynthesis. Although I am not aware of any currently commercial GMO plants with CAM metabolism, some plants with this metabolism include pineapple and cactus.
There is also a seasonal rhythm to many plants’ growth. Plants use various signals from their own growth, and from environmental signals such as day length, to trigger various growth and reproduction processes like flowering, seed maturity and seed shedding from the plant. Row crop plants such as soybean, corn, canola and cotton, regardless of whether it is a genetically modified type or a conventional type, exhibit these seasonal changes in plant growth.
When testing a GMO plant, scientists evaluate many parameters of plant growth and development from germination through final seed production. Plants exhibit natural variability in all growth characteristics. By assessing these characteristics and comparing them to a non-GMO type, scientists can determine if plant growth and physiological processes remain within the natural variation expected except for any targeted effects of the modified trait and trait product. These assessments would also reveal if the seasonal changes in a plant’s growth and development had changed. In this way, we can determine if anything is different about the GMO that is of concern for food, feed or processing.
To conclude, plants don’t sleep as you or I do, but they do follow natural cyclic or seasonal patterns.