What causes grogginess when you first wake up – what about your brain isn’t working?

Question

What causes grogginess when you first wake up – what about your brain isn’t working?

In: 956

Answer 1

To add a little detail since the ELI5 part is done, part of the process of cleaning (yes, physically cleaning) your brain while sleeping involves flooding it with spinal fluid. This is slightly inhibitory of normal functions, so if you wake up during one of the cleaning cycles, you will have difficulty thinking straight until it finishes draining and readjusts. There are a lot more factors involved, but this is one of the coolest ones.