Why am I depressed after a one night stand?

Recently I had my first one night stand. It happened with a guy at a club and it happened very fast without us getting to know each other too much first. The problem is, the next day I felt extremely sad and depressed. I felt like I've been used and felt cheap. I was also sad that he didn't ask me for my phone number even though I wasn't interested in him. I felt unattractive and worthless. Is it normal to feel this way? Do guys ever feel this way too? How can I get over this post-one-night-stand depression?


Does marijuana produce serotonin?

My girlfriend tells me she uses marijuana to calm herself if she is having a stressful day. She has been doing this for many years. She says smoking pot is like self-medicating — it is better than using anti-depressants. She also claims smoking pot helps with depression because of how it helps produce serotonin in the body. What is serotonin and how does it help depression? Does smoking pot really help with managing your anxiety, depression, etc.?