GABA is a neurotransmitter that shows up once in a while that’s linked to a number of various medical and psychiatric disorders. One of the more recent studies was published in the 11/08 issue of Sleep (a summary can be seen here). Chronic insomniacs were found to have 30% less GABA activity in their brains. This finding could be misinterpreted to imply that because of low GABA levels, people can have insomnia. Let me explain.
GABA is one of numerous neurotransmitters in the brain that sends messages from one part of the brain to another. High GABA levels are associated with a calming, relaxing effect, whereas low levels are associated with anxiety and stress. Conventional wisdom says that if this is true, let’s increase GABA levels with supplements. The same can be said for various other neurotransmitters, hormones or vitamins that we use as supplements. In many cases, replacing what’s missing can certainly help, but you’re still not addressing what’s actually causing the lowering of these substances.
If you look in the research literature (and on the internet), you’ll see many studies linking stress and low GABA levels. Another study showed that practicing yoga increases GABA. This is why any method or discipline that is calming or relaxing can raise your GABA levels. So it’s not a lack of GABA that gives you insomnia, per se, but there’s something else that is causing insomnia and low GABA levels.
This is a problem that we see with almost every area of modern medicine, where we’re great at finding associations, but not very good at solving the root of the problem.
The common thread with all these studies goes back to stress. Yes, we have many different types of stress in our lives that can lead to insomnia (financial, work, family, poor diets, toxins, etc.), but what I’m suggesting is the possibility that due to our unique upper airway anatomy, all of us are somewhat susceptible to physiologic stress due to an inability to breathe properly at night. External stresses (psychologic, emotional and physical) can also aggravate this internal, physiologic stress.
The extreme end of this spectrum that I describe is called obstructive sleep apnea. But even if you’re "normal," having a narrowed upper airway anatomy can predispose you to microbstructions and arousals, leading to a physiologic state of hyperarousal. These people won’t officially meet the criteria for sleep apnea. Many of these people will also not be able to sleep on their backs, since that’s when the tongue falls back the most, due to gravity.
If you measure neurotransmitter levels in these patients, of course they’ll have abnormalities. This is why chronic insomnia is linked later in life to so many other medical conditions such as depression, diabetes, hypertension, and heart disease. Notice that these are all complications of obstructive sleep apnea.
This is not to say that we should stop everything we do to treat insomnia. Cognitive Behavioral Therapy (CBT) is a great way to calm the mind and develop good sleep habits. It’s even been found to work better than sleeping pills. My only concern is what happens to these people many decades later, even if their insomnia is initially cured.