great article about tiger and his swing changes. long but good read.
"HE HAS SAID that he does not sleep for more than two or three hours a night. A typical workday starts every morning at 6:30 and extends more than 12 hours -- through three workouts, two range sessions, two practices on the putting green, one short-game session and two nine-hole practice rounds -- until it ends for dinner at 7. Day after day after day. So intense is his focus that he routinely experiences self-described blackout moments on the course; he cannot recall actually hitting many of the shots that everyone else remembers him hitting, regaining consciousness only as his back finishes its rotation and as his hands come to rest just above his left ear, the ball rising into the distance. To put his crying newborn daughter to sleep in the middle of the night, he did not simply rock her while watching TV; he has described carrying the infant to the gym in his house, situating himself on the leg press machine with her on his lap and doing 600 repetitions until she had fallen asleep."