Ancient legend says when you can't sleep at night it's because you are awake in someone else's dream.

Legends aside, we've all had those nights where, for some unknown reason, you just cannot get to sleep. Your brain seems to be perfectly happy to carry out a full analysis of every single thought you had that day and a replay of every conversation you had to boot. But if you frequently have trouble getting to sleep or staying asleep you could have a sleep disorder. Here are the five top facts you need to know: 1. The symptoms of insomnia correspond to difficulties with initiating and maintaining sleep, or at a more basic level poor quality sleep. To achieve disorder 'status', sleep disturbance cannot simply be because of restricted sleep opportunities (i.e. having children!), or environmental factors (his snoring). 2. Doctors will only diagnose you with insomnia if your daytime behaviour is affected as a result of your sleep difficulties. Daytime impairments are measured in relation to symptoms such as fatigue, concentration levels, or if your work is suffering. 3. Another marker of insomnia severity relates to the frequency, length, and persistence of your symptoms, which, for an insomnia diagnosis, is usually set at three nights per week or more and persisting for at least one month. 4. If you are older, a woman, or do regular shift work you are statistically more likely to develop insomnia. Research also suggests that about 40 percent of all people with insomnia also experience a co-occurring psychiatric condition. Specifically, depression and anxiety have been found to be highly prevalent in those with an insomnia diagnosis, compared to those without. 5. A variety of herbal and prescription medications are available for the treatment of insomnia symptoms. However, given that behavioural and cognitive processes are thought to underlie the maintenance of insomnia, it makes sense that therapy should target these issues directly. The world-renowned American Academy of Sleep Medicine (AASM) recommend and endorse Cognitive Behavioural Therapy for Insomnia (known as CBT-I), an evidence-based form of treatment that supports techniques to improve sleep. Other methods known to improve the symptoms of insomnia include progressive muscle relaxation and another form of therapy called 'biofeedback'.