Ambient Somnambulism, or The Zombies Among Us
Ambien is a sleep aid, a class of drugs known as hypnotics. For those pharma geeks, it is not actually classified as a benzo, but does have bind with high affinity at the ω1 binding sites on α-1 GABA-A subunits. Typically prescribed for the treatment of insomnia, it has a short half-life of 2-3 hours. Thus, a crucial part of the dosing regimen is to take the drug only when you know you are going to get at least 8 hours of sleep. Apparently, those who are forced to wake up earlier experience some interesting side effects, as can those who take the drug with alcohol.
Sleepwalking and sleep-eating: A small subset of Ambien users will sleepwalk and even sleepdrive when they use the drug. The scant literature on the subject suggests that those who were sleepwalkers in childhood, or those who have had brain injuries, are more likely to experience this set of side effects.
Memory loss also occurs, and anecdotal reports suggest that some Ambien users have actually raided the fridge while somnambulating and put on a substantial amount of weight, with no recollection of doing so. Others have apparently found themselves in car wrecks or pulled over by the police, with no recollection as to how they got there (although I personally find this a little too convenient).
I find this phenomenon intriguing for two reasons. One is zombies. No, not the Romero flesh-eating sort. In philosophical circles, much discussion occurs over zombies-- specifically, whether the existence of an entity that looks, acts, and responds normally but with no consciousness is possible. Can there be a human who goes to work, has a wife, coaches little league, but has no conscious experience? Perhaps here we have a way to investigate the possibility. Does Ambien shut off excitatory (or activate inhibitory) neural circuits that directly disengage a "consciousness" module or diffuse neural net? Can a somnambulant Ambien user "learn" new things, be they cognitive or motor skills, and can these new skills be performed/recalled at a high skill level when fully conscious, despite a lack of mnemonic recall for the event itself? Or can he/she be made to become fully conscious while in this state e.g. through the use of pain or loud noise, or direct stimulation of other neural circuits? To what extent does Ambien actually interfere with conscious perception? Do Ambien users display their normal personality when they are having a somnambulatory event? Can we stick them in an MRI or EEG and observe how activation patterns differ when the person is conscious and when they are on Ambien? David Chalmers is likely wetting himself at the experimental possibilities, while Daniel Dennett won't be particularly thrilled.
The other reason I find this intriguing has to do with memory. Perhaps the individual is fully conscious, but simply doesn't remember what happened once the meds are out of his or her system, simply because Ambien mucks up memories. Certainly there have been reports of memory impairments in patients who took Ambien but didn't get their full 8 hours of sleep. We may have an interesting drug with which to study the neural mechanisms behind the encoding and retrieval of memories. Certainly there has been quite a bit of research into the memory-altering effects of benzodiazepines and GABA-ergic compounds.
As I mentioned at the start of this post, one paper in the lit search struck me as particularly interesting, because it suggests that certain combinations of drugs may be used to elicit the somnambulist effect, and while one drug (zolpidem, in this case) may not elicit somnambulism, the system could be primed for the effect upon introduction of the second drug (valproic acid, in this case). While this may not hold true for all patients (particularly at one dosing regimen), common mechanisms may be elucidated in this manner. Conceivably we could build an inductive explanation to these phenomena.