If I learn something new in the morning, very often I still remember it in the afternoon, even though I haven't been to sleep yet.
Neuroscientists/psychologists/etc believe [0] humans have four tiers of memory: sensory memory (stores what you are experiencing right now, lasts for less than a second); working memory (lasts up to 30 seconds); intermediate-term memory (lasts 2-3 hours); long-term memory (anything from 30 minutes ago until the end of your life).
We don't need to sleep to form new long-term memories – if at dinner time you can still remember what you ate for breakfast (I usually can if I think about it), that's your long-term memory at work. What we need sleep for, is pruning our long-term memory – each night the brain basically runs a compression process, deciding which long-term memories to keep and which to throw away (forget), and how much detail to keep for each memory.
Regarding your juggling example – most neuroscientists believe that the brain stores different types of memories differently. How to perform a task is a procedural memory, and new or improved motor skills such as juggling are a particular form of procedural memory. How the brain processes them is likely quite different from how it processes episodic memories (events of your life) or semantic memories (facts, general knowledge, etc). Sleep may play a somewhat different role for each different memory type, so what's true for learning juggling may not be true for learning facts.
Neuroscientists/psychologists/etc believe [0] humans have four tiers of memory: sensory memory (stores what you are experiencing right now, lasts for less than a second); working memory (lasts up to 30 seconds); intermediate-term memory (lasts 2-3 hours); long-term memory (anything from 30 minutes ago until the end of your life).
We don't need to sleep to form new long-term memories – if at dinner time you can still remember what you ate for breakfast (I usually can if I think about it), that's your long-term memory at work. What we need sleep for, is pruning our long-term memory – each night the brain basically runs a compression process, deciding which long-term memories to keep and which to throw away (forget), and how much detail to keep for each memory.
Regarding your juggling example – most neuroscientists believe that the brain stores different types of memories differently. How to perform a task is a procedural memory, and new or improved motor skills such as juggling are a particular form of procedural memory. How the brain processes them is likely quite different from how it processes episodic memories (events of your life) or semantic memories (facts, general knowledge, etc). Sleep may play a somewhat different role for each different memory type, so what's true for learning juggling may not be true for learning facts.
[0] https://en.wikipedia.org/wiki/Intermediate-term_memory