First, be honest about which kind of tired you are. If you are genuinely sleep deprived, the best study move is often a short rest, because forcing a shutting brain to read wastes an hour for almost nothing. But if you are just low on energy or unmotivated, you can work with that.
When energy is low, lower the difficulty, not the effort. Instead of trying to learn a hard new concept, do lighter tasks that still count, like revising old notes, making flashcards, solving easy practice questions, or organising what you will study tomorrow. This keeps you moving without demanding full mental power. A ten minute walk, a glass of water, and some fresh air genuinely help too, because dehydration and stuffy rooms make tiredness worse.
Use very short study blocks on low days. Tell yourself you will study for just fifteen minutes, because starting is the hardest part and momentum usually carries you further once you begin. Avoid heavy sugar and big meals right before studying, since they cause an energy crash. And if you keep feeling drained every single day, treat that as a signal to fix your sleep, food, and screen time, not as a personality flaw.
Example: On a tired evening, instead of skipping study entirely, spend fifteen minutes making flashcards from today’s class. It is low effort but still real progress.
One practical tip: Match the task to your energy. Save hard new topics for your fresh hours and give tired hours the light revision work.