1 year old Chocolate Lab excessive sleeping

Question
I have a 1 year old female chocolate lab. Over the past 3 or 4 days she has been not been herself. She is normally a nut ball, running around, very hyper, and full of energy. Now she is all snuggles, sleeping, or just laying around. She does this during a growth spurt but she doesn't have any extra skin to grow into. Also, this past week has been very hot, near the 100s, so i don't know if the heat is contributing to it. She is eating normally, having no bathroom trouble, no trouble walking, and no other physical illness signs. I would just like to know if this excessive sleeping is normal for her age or if I need to take her to the vet. Thank you.

Answer
I hate to send you to the vet if it is just the heat.  If you are comfortable taking her temperature, and it is above 102 F, I would take her to the vet.  

I have noticed my dogs are less active in very hot weather even when spending most of their time in the air conditioned house.