system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is insomnia different from having a bad sleep schedule or just plain restlessness? How is insomnia diagnosed?
gpt
Insomnia literally means "want of sleep." It's a general term for any sleep disturbance, not a specific diagnosis in itself.

Insomnia can be caused by a bad sleep schedule. Not sure exactly what you mean by restlessness, but if you're talking about a night of bad sleep, that's pretty much the definition of insomnia. 

There are thousands of different things that can affect sleep. It's normal to have a couple of nights of weird sleep in a month, but if you often can't sleep well, talk to your doctor to get to the bottom of your situation.