Sleep Patterns Under Caffeine Exposure

To record the sleep under short exposure to caffeine, 1-, 10-, 20-, and 30-day-old w¹¹¹⁸ male flies were transferred to locomotor activity glass tubes (65 mm length, 5 mm diameter) containing cornmeal dextrose medium for acclimatization 12 h prior to the start of the experiment. These flies were transferred into locomotor activity glass tubes containing cornmeal dextrose medium with different concentrations of caffeine (0.0, 0.5, 0.75, and 1 mg/mL) just before ZT 00 on the day of locomotor activity recording. Sleep was recorded by using the Drosophila Activity Monitors (Trikinetics, USA) for 24 h under LD in a cooled incubator (MIR-154, Panasonic, Japan). On the subsequent day, at ZT 00, these flies were transferred back to fresh cornmeal dextrose medium without caffeine to record their sleep rebound for the next 24 h. Activity counts were measured at every 1 min interval and sleep was defined as 5 min or more of continuous inactivity. Sleep parameters such as total sleep duration, sleep bout length, sleep bout number, sleep latency, and sleep in 1 h were analyzed using Sleep and Circadian Analysis MATLAB Program (SCAMP) [27 (link)]. To confirm the results, each experiment was replicated three times with a sample size of 25–32 flies in each replicate. The data obtained from one such biological replicate is used in the results and figures.