I haven’t slept or I haven’t been sleeping for 2 days I’m just wondering what is the difference between the following 2 sentences? I haven’t slept for 2 days. I haven’t been sleeping for 2 days. The context is about someone regrets about a mistake he has made. and when can I use each of them?

language acquisition "Use it or lose it"

In my opinion You don't learn language You acquire  it in the same way You acquire your first language .

i try to understand why we lose the language which you learn  if we don't use it for two or 3 weeks i found after 15 days Your brain start to  forget this language  gradually and if we ask Ourself  why we don't lose our mother tongue after this period , we will find that it depend in our brain  specifically depends on neuroplasticity  when you learn  language chemical signals increase changes in your short term memory but induce didn't change the structural  changes in your long term memory .

change long term memory depends on behavior and to change Your behavior you have to practice so if you don't use it lose it

Need Tips For English Ielts i prepare myself for IELTS and i want to get high score so i need to know which the best way improve my studying and my English Like you think read books more helpful in the Exam or watching movies what is the best effective way You think can help me to study English for IELTS certification ? and when i decide i can take it now ?

what is the difference between universal and international ? actually i want to know the difference between universal and international and when to use each one of them