Just to throw in my 2 cents worth. I did crystal one time (snorted lines) one afternoon and it was my 2nd time doing chems (first time was what is turned as kat) and looking back, the difference is as clear as night and day. Whilst on Crystal it was a much intense high but my gosh, the down was absolutely horrendous! Like @CuriousDallas says, was tired but couldn't sleep at all. I had the session on an afternoon, so that entire night following I didn't sleep a wink. Come morning, I started to feel numbness on my finger tips and face but subsided after I forced myself to have some toast a short nap....the rest of the day I was ok, but still felt weird and spaced out. Eventually the numbness returned with a huge vengeance and I had to call my friend to come over to attend to me. She called the ambulance and I was admitted into A&E and kept overnight for observation. Diagnosis was that I had severely low blood sugar and probably as some of you said, coupled with anxiety, brought me low and down. I was discharged the following day but spent the next 48 hours or so wallowing in the most blackest of depression. Hence, I never ever will do crystal again. Also on hindsight, I didn't have a "teacher" to guide me through the chem experience. A few years later, I met this guy who I formed a good sexual relationship with and he was a great teacher and very knowledgeable and guided me. I never had a bad chem experience since.
Just to end, I'm glad your friend is fine!