Is it normal to feel sleepy and tired after eating at any time of the day?

Common, not normal. This is a fairly common experience, especially among people with diabetes, or whose bodies are starting to struggle to maintain stable sugar levels throughout the day. Keep a log of when you feel this way, and what you've eaten in the 2 hours just before that. Many people find that eating fewer carbs (sugars/starches) or walking after eating help them avoid feeling this way.
Is can be. Some people it can be. This may have to relate to glycemic index. In general, however, no, not normal. There is natural circadian dip after lunch. See someone to make sure it is not sign of sleep disorder due to poor nocturnal sleep.