How much sleep do you need to be functional?

Last night I got to sleep around 11, woke up at 2 from a weird dream, back to sleep around 2:30, woke up at 4:30 from a series of texts, back to sleep and then another text at 6:30, back to sleep and woke by my cat at 7:30. I'm too exhausted to do much today and I have a red eye flight to catch tonight 😵😴