If you've ever awoken in the morning, yawned, and stretched your arms, you've experienced pandiculation.
Use the noun pandiculation to describe the particular sleepy combination of yawning and stretching. It's a somewhat obscure but impressive way to talk about a universal phenomenon. Animals are prone to pandiculation too, extending their paws in a stretch and yawning widely. The Latin root is pandiculari, "to stretch oneself," from pandere, "to stretch."