Post workout light headedness

So in the late afternoon I had a great chest and legs day (do them both on the same day cause my schedule permits gym time 3 days a week )and then followed by a slow hot yoga session in the early evening. Made sure to hydrate before during and after my workouts and yoga session. Fell asleep on the couch and front of the tv and then woke up a couple hours later. Turned off all the lights and went to bed. However as soon as I put my retainer in and laid down in bed I started to feel light headed and hard to breathe. I’m not sure if it’s anxiety. What should I do ?