A sleep disorder characterized by an inability to sleep and/or to remain asleep for a reasonable period during the night. It the most common of 60 or more sleep disorders.

Persons most commonly affected: All age groups and both sexes.
Symptoms and indications: The predominant complaint is difficulty initiating or maintaining sleep, or nonrestorative sleep, for at least 1 month. 
Causes and risk factors: Insomnia is a common side-effect of some medications, and it can also be caused by stress (related to work, school, health or family concern), emotional upheaval, physical or mental illness, alcohol and caffeine, dietary allergy and poor sleep hygiene. Insomnia is a major symptom of mania in people with bipolar disorder, and it can also be a sign of hyper-thyroidism, depression, anxiety or other ailments with stimulating effects. Hormonal changes (e.g. menopause) can also cause insomnia.
Prevention: Some traditional naturals for insomnia have included drinking warm milk before bedtime; taking a warm bath 1 or 2 hours before bedtime; exercising vigorously for half an hour in the afternoon; eating a large lunch and then having only a light evening meal at least three hours before bed; avoiding mentally stimulating activities in the evening hours; and paradoxically, making sure to get up early in the morning and to retire to bed at a reasonable hour. Sufferers of insomnia should avoid all caffeine, nicotine and alcohol. Caffeine is often a factor in insomnia, including insomnia in night-shift workers. Caffeine is found in coffee, tea, cocoa, Kola nut (this includes all cola drinks); it is also found in \"energy\" sodas like Red Bull and similar, chocolate bars and other candy. Drink herbal teas or plain water instead of caffeine-containing liquids. Do not smoke before bedtime. The bedroom environment should be conducive to sleep. Some people are very sensitive to light while others are sensitive to noise. The bedroom should be dark and quiet at night. Try to avoid thinking of worries, fears and perhaps phobias. Such concerns are likely to prevent the mind from resting and may be exaggerated. It is a good idea to write down any particular worries that are bothering you, keeping a diary or noting down your emotions and thoughts can be very cathartic and any particular worries can be revisited and dealt with at a more appropriate time.