insomnia

1 - By far the most common sleep complaint is insomnia.

2 - People who experience insomnia fairly regularly, though not constantly, are said to have intermittent insomnia.

3 - Excessive consumption of caffeine can result in restlessness, insomnia, and even delirium.

4 - Insomnia, the inability to sleep, is not a disease but rather a symptom of an underlying problem, much as a cough may be a symptom of a cold or an allergy.

5 - Sleep researchers have found that established cures for insomnia, for instance counting sheep, do not work.