The Power of Amnesia

Insomnia provokes many controversies. One of the more heated at the recent Sleep Research Meeting in Minneapolis was about why sleeping pills work - do they induce sleep? Or do they just make people forget they were awake during the night?

Lots of people, including Mike Perlis, now at the University of Pennsylvania, suggest the latter is very important.

What Are the Clinical Definitions of Insomnia?

Multiple. The problem is that the data are by their nature phenomological - this is what people report. The results include: this group could not fall asleep or stay asleep well from childhood (childhood or general insomnia); this cohort worries so much about sleep they can't sleep (psychophysiological insomnia); this group sleeps wells once they get to sleep, but can't get to sleep for a long time (early insomnia); this bunch of folks sleeps well but wakes too early and can't fall back to sleep (late insomnia.)

Insomnia researchers know the populations they study are very heterogeneous, and include many people who subjectively tell you they sleep hardly at all, but once ensconced in a lab sleep rather well. This common mismatch between subjective and objective sleep leaves many researchers scratching their heads.

The many puzzling results have led others to classify insomnia quite differently. Technology leads the way.

A group at the University of Pittsburgh has been doing very careful functional MRI studies. They find that many insomniacs have rather strange results in their frontal lobes - overactive ones, that they've tried to cool off with water filled cooling caps.  The preliminary results of caps has been quite good.

Others have looked to the Internet to study insomnia. Research groups in Amsterdam and Glasgow have asked insomniacs to write in about their symptoms using the Internet. Thousands and thousands have complied, aided by websites that give them feedback and much information on sleep. These researchers have been parsing their Internet subjects - most of them will never been seen in person - by their symptom groups, and finding all kinds of assortments that do not fit standard clinical criteria.

What most people do not dispute is that sleeping pills often make people feel better about their sleep. After that, controversy reigns.

How Do Sleeping Pills Make Us Sleepy?

The most commonly used sleeping pills of old were the benzodiazepines - these drugs with combined benzene and diazepine rings have been used to treat insomnia and anxiety since the 1960s. The population includes diazepam (valium,) clonazepam (klonopin,), lorazepam (ativan,) and many others. They work by settling on nerve cell benzodiazepine receptors that live on cell membranes, information receptors which have existed through evolution for many tens, perhaps hundreds of millions of years.

Many newer drugs like zolpidem (ambient) and zaleplon (sonata) claim to be non-benzodiazepines. Yet this "advantage" is highly disingenuous. Most of these newer sleeping pills work by stimulating one of the main benzodiazepine receptors, of which there are three main types. Effectively the newer drugs are just a more selective version of the older benzodiazepines.

Old line benzodiazepines do much more than induce sedation. They act as anti-anxiety agents; muscle relaxants; and create anterograde amnesia - forgetting the period before their use. This anterograde amnesia - literally making it difficult for memory to get encoded - is one reason they may also work to help prevent post-traumatic stress in people who have witnessed horrific events.

In general, sleeping pills induce more sleep than usual in insomniacs - amounts vary from a few minutes to an hour, but generally down around 10-20 minutes more sleep. The sleep they produce is not the same as normal sleep, with changes in slow wave sleep and often decreases in REM sleep.

Why Do Insomniacs Like Sleeping Pills?

Drug companies aver that sleeping pills work because they produce more sleep. However, many researchers, like Perlis, are skeptical. They note that some of the early effects of the newer pills have been considered as more akin to coma than sleep, and that much of insomnia remains highly subjective. If people forget they woke up, they will feel better. And these drugs do produce much amnesia - forgetfulness for what took place during the night. Some of the newer ones like ambien have been implicated in bizarre sleepwalking episodes, where people appear both awake and asleep and drive their cars or clean their homes without awareness of what they're doing - during or after.

Curiously, sleep itself induces amnesia - as a normal function of sleep. Many people cannot accurately recall the last few minutes before they fell into slumber. Sleep also tends to make people forget their arousals - the many times they woke up. Even "perfect" sleepers awaken for 5-30 seconds a dozen or two dozen times a night, and poster no recollection of awaking. A recent research abstract at the national Sleep Research meeting argued that about 5 minutes was necessary for most people to even recall being awake.

What Are the Problems With Sleeping Pills?

Tolerance, addiction, and withdrawal - the other side of the coin of the many things they usually do. Some argue that chronic use of sleeping pills can lead to chronic and permanent memory loss - but the "meta-analysis" that drew that conclusion looked at data that were flawed, not noting concurrent diagnoses of addictions and many mental disorders. Others researchers argue that the sleep produced by sleeping pills is never truly normal sleep.

Why Are Sleeping Pills So Popular?

There are many reasons, including 1. People do fall asleep more quickly, particularly at first 2. They do far more than just induce sleep.

The common sleeping pills - even some of the newer "non-benzodiazepines" - act as anti-anxiety agents. In an anxious age, people appreciate that effect - particularly as anxiety also leads to sleeplessness.

And muscle tension and anxiety often induce sleeplessness and exacerbate pain and aches. So their muscle relaxant properties are also welcomed.

Finally, there is the amnesia produced by sleeping pills. Amnesia is produced for both positive and negative thoughts - and many insomniacs have much of the latter, as many also suffer lesser or greater degrees of depression.

Bottom Line

Sleeping pills do a lot beyond sleep - which may account for much of their popularity. Unfortunately, they also create many unwanted effects. However, their capacity to induce amnesia may account for why so many pill takers feel they slept "better" through the night - particularly as they can't remember bad dreams and nightmares quite as well.

As politicians and clinicians know, amnesia has its uses.

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