All organisms have different cellular energy allocation (CEA) at different times depending on the situation of storage and consumption of energy. Presence of an organism in different environmental conditions, especially dark – light cycle, induce different levels of physical and metabolic activity and this subject can make difference in the amount of reservation and consumption energy at different times of the day. In this investigation it was assumed that Aphis gossypii has different CEA at different times of day. The effect of two photoperiods consist of 16 hour photophase and 8 hour scotophase as a natural light condition and constant light as an abnormal lighting condition have experimented every four hours at different zeitgeber times (including 0 (24), 4, 8, 12, 16 and 20). CEA was calculated according to Foray (2012) protocol for available energy including total carbohydrate, total lipid, total protein and glycogen and Decoen-Janssen (2000) and Yuval (1998) protocols with a little change for energy consumption. For doing the experiments, frozen adult aphids of the same age were used. These aphids were reared under these lighting conditions at 25±10c and 65±5% relative humidity. At the natural light condition, 16 hour photophase and 8 hour scotophase, the most CEA derived from the dark hours that have a significant difference with lighting hours, while the most CEA at the constant light was at ZT8, i.e. noon time. This difference shows that in the induced stress condition of constant light, CEA of organism has reduced more than that hours represented night, i.e. ZT16 until ZT24, in this abnormal lighting condition. Even the amount of CEA has reduced in all ZTs of constant light in compare of normal lighting condition and this subject confirm that existence of an organism in stress condition, has a substantial effect on the amount of its energy.