What is the optimal sleeping altitude?

CAT's medical board of advisors recommends 8,500 -12,500 feet above sea level.

Studies showed the importance of sleeping as high as possible up to 12,500 feet (but no higher).

While the body gets stronger from altitude up to 12,500 feet, scientific data suggests that above 13,000 feet fitness decreases.

• Will sleeping at altitude slow recovery and hurt performance?
• Is there a maintenance schedule to keep the acclimatization effect?
• How does the exposure to simulated altitude compare with natural elevation?
• What are the advantages of simulated altitude?
• Why don't I just train harder at sea-level?
• I already live at high altitude; will CAT's systems still help me?
• How long do I need to sleep at altitude to notice the benefits of Altitude Training?
• What is the optimal sleeping altitude?
• What is the optimal altitude for training?