Low GABA in Primary Insomnia

GABA Deficiency Linked to Primary Insomnia

GABA is the main inhibitory neurotransmitter in the mammalian nervous system. Neurons that produce GABA as their output are called GABAergic neurons, and have mainly an inhibitory action at receptors in the nervous system.

A new scientific study in the Nov. 1,2008 issue of the journal Sleep demonstrates a specific neurochemical problem in adults who suffer from primary insomnia. This finding gives greater insight to the understanding of the condition’s pathology.

The study indicates that gamma-aminobutyric acid (GABA), which is the most common inhibitory transmitter in the human brain, is reduced by nearly 30 percent in individuals who have been suffering from primary insomnia for more than six months. The lower GABA levels suggest that primary insomnia is a manifestation of a state of hyperarousal. This hyperarousal condition is present during both waking and sleep.

Low GABA levels in the brain of individuals with insomnia suggests physiologic overactivity is present. This leads to excessive thoughts and emotions.

GABA lowers global activity in many brain areas and helps the brain to “shut down.” The problem of a “racing mind” and an inability to shut down at night is a common complaint of people with primary insomnia.

Chronic insomnia, or symptoms that last for at least a month, affects about 10 percent of all adults in industrialized countries and is the most common sleep disorder. Most often insomnia is a companion disorder, present with another medical illness, mental disorder or sleep disorder. Insomnia is also associated with certain medications or substances. 25 percent of people suffering from insomnia are considered to have primary insomnia, which is a difficulty falling asleep or staying sleep in the absence of other medical conditions.

Reduced GABA levels in the brain also have been observed in major depressive disorder and anxiety disorders. Primary insomnia has many features in common with anxiety and depressive disorders. Sleep disturbance, elevation in anxiety, and impairments in concentration and energy commonly occur in these conditions. Primary insomnia is an important risk factor for mood and anxiety disorders. There is the possibility that GABA deficiencies seen in people with mood and anxiety disorders may be related to disturbances in sleep.