Meditate mindfully instead of sleeping Often around 2:00 p.m. after eating, my body falls tired. So I have to stop studying. I am myself a long term meditator, but I rarely meditate when I am tired. Is meditation a good substitute for sleep? In other words, around 2:00 p.m., if I am going to meditate mindfully for an hour instead of sleeping, will this meditation be able to replace sleep?
Often around 2:00 p.m. after eating, my body falls tired.

Might be a good idea to investigate and tackle the root cause to your tiredness first. Is it because you don't get enough sleep at night? or you usually eat a big lunch? or the workload is too stressful?...etc. It's actually not a bad idea to take a brief afternoon nap for 20-30 minutes to recharge your battery so you can come back to work all fresh and ready. Anyway, you should listen closely to your body. Try test it out/experiment with both of them, and see how your body reacts..