Methods

To test the effects of photoperiod changes on P. roborovskii, three female Roborovski dwarf hamsters of same age and weight were obtained and placed in three separate cages. Each cage had 10g of Econutrition hamster food and 120ml of tap water. The experiment lasted about two and a half weeks and all initial amounts of hamster food was pre-measured for the entire experiment. To control the lighting, all three hamsters were placed in a light-controlled room where a desk lamp was centered above them. A light timer was used to automatically control the lighting and was first set for the control time 12 hours of dark and 12 hours of light. On the first day of the experiment, hours of dark started at 9:00p.m. until 9:00 a.m. the following day, while the hours of light started at 9:00a.m. until 9:00p.m. Each day at 9:00p.m., the hamster's food and water was collected and measured then replaced with initial amounts. The control time was repeated for two more days. To allow the hamsters to adjust to the light change, each photoperiod was set for three days. Every three days by changing the light timer, the photoperiod was increased by three hours until the photoperiod reached 6 hours dark and 18 hours light.

To decrease the photoperiod, the same procedure was followed starting at the control time of 12 hours dark and 12 hours light for three days. The hours of light decreased by three hours every three days until the photoperiod reached 18 hours of dark and 6 hours of light.