Make sure you drink plenty of water when you do a lot of mental work like photoreading, studying, mind mapping. You might want to check this post for discussion on feeling tired.
http://www.learningstrategies.com/forum/ubb/Forum8/HTML/002576.html An incubation period of at least 20 minutes allows you to relax and let your mind process the information... the longer (overnight) the more you are telling your body/mind that you are relaxed about the material. Once you've learned this relaxed approach of trusting the inner mind you can experience almost instant spontaneous activation from time to time.
However the whole process is training. The brain is a muscle and needs to be exercised. You cannot do weight training just once and expect to have muscles like body builder straight away. It's the same with the brain. You need to practice and build on your successes over time your optimal incubation period for certain material becomes shorter to almost instant. Other material you might still need to leave overnight.
Keep up the good work.
Alex
