Dictionary

fibromyalgia: Fibromyalgia causes chronic pain throughout the body, which often makes sleeping difficult. People with the condition can experience sudden brain activity during the night that resembles waking brain patterns. These increases in brain activity hinder the ability to enter deep, restful sleep.

hypersomnia: A condition that can include excessive daytime sleepiness, long sleep periods, and excessive amounts of deep sleep. Hypersomnia is usually a symptom of an underlying disorder, such as narcolepsy and apnea.

hypnagogic hallucination: Also spelled hypnogogia, describes vivid dream-like auditory, visual, or tactile sensations, which are often accompanied by sleep paralysis and experienced when falling asleep or waking up.

hypothyroid conditions: Can mimic sleeping problems, but require specialized medical treatments. The term hypothyroid means that the thyroid gland is under-active. Both physical and mental functions suffer if hypothyroidism is present. The fatigue that accompanies the condition appears similar to the weariness associated with insomnia.

hypoventilation: A condition in which the lungs do not draw in sufficient air. Although humans need less air when asleep, hypoventilation can lead to fragmented rest due to decreased oxygen levels. The condition can be caused by obesity, respiratory problems, or brain mechanism difficulties. A form of apnea, called central sleep apnea, occurs due to the brain mechanism-caused hypoventilation.

idiopathic: A type of hypersomnia. Idiopathic hypersomnia is long-term, excessive daytime tiredness without a definite cause. The condition resembles narcolepsy, but lacks the sudden shifts from a waking state directly into the REM, or dreaming, state. Instead, people suffering from idiopathic hypersomnia experience long phases of deep, non-REM, slumber, which can last up to two hours at a time.