Insomnia is defined as inadequate or poor-quality sleep characterized by one or more of the following: difficulty falling asleep, difficulty maintaining sleep, waking up too early in the morning, or sleep that is not refreshing. Insomnia also involves daytime consequences such as fatigue, difficulty concentrating, and irritability.
Periods of insomnia lasting between 1 night and a few weeks are defined as acute insomnia.
Chronic insomnia refers to sleep difficulty occurring at least 3 nights per week for 1 month or more.
Insomnia may be associated with specific sleep disorders, including restless legs syndrome, periodic limb movement disorder, sleep apnea, and circadian rhythm sleep disorders.
- Restless legs syndrome is characterized by unpleasant sensations in the legs or feet that are temporarily relieved by movement. Symptoms are worse in the evening, especially when a person is lying down and remaining still. The sensations cause difficulty falling asleep and are often accompanied by periodic limb movements.
- Periodic limb movement disorder is characterized by bilateral repeated and rhythmic, small-amplitude jerking or twitching movements in the lower extremities and, less frequently, in the arms. These movements occur every 20 to 90 seconds and can lead to awakenings, which are usually not noticed by the patient. Often the patient reports that sleep is not refreshing. In many cases, the bed partner is more likely to report the movement problem.
- Obstructive sleep apnea is most commonly associated with snoring, daytime sleepiness and obesity but occasionally presents with insomnia.