Can I wake up at any time of night/early morning, say birchat haTorah, and begin to learn?
Is there any time of night/early morning I cannot do this?
Is there ever a time in which learning Torah is not allowed?
For example, if it's about 25 minutes to alot hashachar, do I wait for alot hashachar to say all the morning brachot, including birchat haTorah, and then learn Torah, or can I say birchat haTorah even 25 minutes before alot hashachar and learn Torah, and then at alot hashachar or a bit after that time, say the birchat hashachar?