Aim for as much as nine hours. Take naps.
Top performers sleep more. In studying sleep patterns among conservatory students, Anders Ericsson discovered that, “The weekly amount of sleep during the diary week did not differ for the two best groups and averaged 60.0 hr. This average was reliably longer than that for the music teachers, which was 54.6 hr… Hence the two best groups, who practice more, also sleep reliably longer.“
And napping has well-documented restorative effects. “NASA’s Fatigue Counter Measures Program has found that a short nap of just forty minutes improved performance by an average of 34 percent and alertness by 100 percent.” (Loehr & Schwartz)
Famous nappers include da Vinci, Napoleon, Edison, Kennedy, Thatcher, Reagan, and Clinton. Churchill summarized it thus:
You must sleep some time between lunch and dinner and no halfway measures. Take off your clothes and get into bed. That’s what I always do. Don’t think you will be doing less work because you sleep during the day. That’s a foolish notion held by people who have no imagination. You will accomplish more. You get two days in one—well, at least one and a half, I’m sure. When the war started, I had to sleep during the day because that was the only way I could cope with my responsibilities.
K. Anders Ericsson et al. 1993. The Role of Deliberate Practice in the Acquisition of Expert Performance. Psychological Review
Jim Loehr and Tony Schwartz. 2003. The Power of Full Engagement. Free Press