Sleepy after Drinking Smoothies. Is this normal ?

I started making smoothies for the first time this week and I noticed that after I drink my smoothie.I am very fatigued. The only day that I didn’t have a smoothie, which is today, I am wide awake and not sleepy. Is it normal to feel sleepy after drinking a smoothie.

S/N: I also have hypothyroidism not sure if that plays a role.