Waking up at 4am is not a flex. 4am gives an 1-2 extra hours a day with no distractions where meaningful work can be done. 

That is a minimum of 365 distraction free hours in a year. 

It doesn't really matter what time you get up or go to bed. The important thing is what you do with those hours. 

Regardless finding at LEAST one hour a day that is distraction free will add massive value to your day.