The basic definition of insomnia is the inability to sleep. This can vary, some individuals may not be able to sleep at all whilst others may not be able to sleep until 2 or 3am. This kind of partial insomnia seems very common.
It is not just the inability to sleep that makes up insomnia it is the inability to shut down and relax enough to sleep. Most people who suffer from insomnia to whatever degree will tell how tired they feel. However when it comes time to sleep there seems to be a restlessness that takes over. Whether it is working, engaging in social media or streaming Netflix show these are the things that ultimately stop you from trying to sleep.