I have tended to stay at about Induction Level of carbs - possibly due to thyroid problems weight loss is slow but steady. There are times when I need a higher level.

Very occasionally I do get lightheaded. And yes I have increased the carb level for that day - usually have a Mini eclair and a slice or two of low-carb bread as well as extra helping of LC vegetables. It happens sometimes when I have not been eating meals regularly or gone long periods without food.

As for sleepy - I don't know about that. LCing has actually had the reverse effect on me.

Take care.