Disclaimer: Not an expert. When you do a hard workout for the first few times, there are a lot of neural adaptations. These result in very quick gains of stren

Disclaimer: Not an expert. When you do a hard workout for the first few times, there are a lot of neural adaptations. These result in very quick gains of strength within the first few weeks, I think mostly due to better muscle recruitment. At the same time, these neural adaptations are taxing on the brain/CNS. This is especially true of exercises that require intramuscular coordination. In my personal experience it makes it very hard to fall asleep when I learn a new, complex power exercise (e.g. campusing [1]). It also seems logical that you need more sleep for those neural adaptations to take place. Now, once you are experienced in the exercise, there are much less neural adaptations, hence the perceived plateau in strength gains. The way you make gains now, is mostly through muscle growth (hypertrophy) which takes much longer but doesn't tax the CNS as much. This might explain your observation of needing less sleep after intense workouts, now that you have more experience in your sport. Try a new intense exercise and you will likely experience the above described process again. Just don't injure yourself! [1] https://www.youtube.com/watch?v=7ACyeOP-Hxo&t=5m40s https://www.youtube.com/watch?v=7ACyeOP-Hxo&t=5m40s