Sleepy After Work-Out

Hello. Today was my first day at working out and eating light. I'm quit heavy, I get no exercise ever, and eat horribly. So this is what I did..and I'm wondering if it's normal to feel sleepy after a work out....

100 squats, 2 minutes of wall sitting, 2 minutes of planks, 30 sit-ups, 5 push-up (girl style). I did break everything up..like the wall sitting, I did 30 seconds at a time and then went to something else.

Breakfast--fruit and veggie smoothie about 300 calories
Lunch--Tuna with no bread on lettuce leaf--made with light mayo with a side of raw veggies
Snack--Apple and string cheese

My legs feel like spaghetti..so I know I did good. But feeling sleepy??