Always Learning


Can’t we get people to learn stuff while they sleep?

It’s been a dream (pardon the pun) of psychologists, physicians, industrialists and teachers for many many years. Why should eight hours—one third of life—be spent in such a “wasteful” manner?

Now, media hype hopes are rekindled anew with an innovative study from Northwestern treating “phobias” during sleep. What the study shows more effectively is something that sleep is not a light switch where the brain “turns” off, but a time of active—and necessary—learning.

The Study

Fifteen participants are given electric shocks that are behaviorally paired with faces and smells. Then the smells are reintroduced—during deep sleep—also known as slow wave sleep. In slow wave sleep growth hormone is produced, parts of learning and memory consolidation takes place, bizarre sleepwalking usally arises and the body acts like it’s in near coma. It's certainly an interesting time to try "psychotherapy."

If the participants receive the smells that occurred in electric shock their fear “response”—as measured by skin conductance and Functional MRI scans—goes down.


Media and “professional” response—we might be able to treat phobias during sleep using smells or other stimuli. The authors are suitably and sensibly quite cautious about this.

Will Pairing Scary Stimuli During Sleep Really Work to Treat Phobias?

Not yet. 

Reasons against:

1. This was a study of healthy people without phobias. Pairing electric shocks with anonymous faces is not how humans typically develop irrational fears. Plus people who develop phobias often have different genetics, baseline difficulties with depression and anxiety, and thoroughly different environments than those who don’t.

2. Plenty of people experience thoroughly horrible things—like war, rape, and murder—and don’t develop phobias. Others with “minor” stimuli do.

3. Skin conductance may not tell you a whole lot about people’s conscious reactions—which is what happens when a person with a severe spider phobia sees one and leaps out of a boat.

4. There’s no comparison between awake versus sleeping treatments—and no comparison with people who have real phobias. So far, the conscious treatments—gradually exposing people to something they fear—are good but very far from perfect treatments.

5. It’s not that easy to figure out when people are in slow wave sleep—even in fully equipped sleep labs. The presently available commercial devices that proudly tell people how many seconds of deep, REM, stage 1, stage 2, and stage 3 sleep they experienced each night are both inexpensive and inaccurate. Plus it won’t be all that easy to hook up accurate, second by second brain wave records that immediately tell your perfectly timed smell generators to puff out those odors.

6. Many people with even severe phobias do not undergo exposure therapy treatments. Even though it works better than most things, people frequently prefer to take a pill than consciously face down their fears. Will they really hook themselves up at night with EEG machines and smell makers to do during sleep what they disregard when awake?

Real Implications

Northwestern University has a very active sleep research group that is highly productive. Media hyperventilation aside, there’s some useful stuff to learn from this study:

1. Even when people are in deep sleep—so close to coma that it frightens sleep deprived parents of night terror children because they can’t wake the kids up—they are still responding to outside stimuli. That we respond to stimuli throughout sleep is well known to researchers, but most of the public has no clue.

2. Lots of what the brain does is not conscious. Not conscious. Even if we can’t “think about it” such actions are incredibly important. Most of immune function, for one critical example, occurs below conscious understanding and memory. The immune cells know. The brain knows. We don’t.

3. Things done to us while not conscious affect us while awake.

4. Lots of learning goes on in sleep. Lots of remembering and memory gets redone in sleep. Much of the body is replaced during sleep. It all happens—even if you’re not aware of it.

5. Just because something is not conscious does not mean it is a waste of time.

What goes on during sleep may occur “under the hood.” But it’s remaking the whole car under the hood. Thinking your body is some sort of machine is a bad idea.

6. Most studies of the brain only look at conscious material. Some researchers believe the overwhelming majority of brain activity occurs without conscious referents. Yet all too rarely are studies like this Northwestern one looking at what is the largest part of what your brain does.

Seeing is not believing. Remembering is not necessarily accurate recall.

The body is a giant information system. Most of its thinking is outside the box—but inside your head.

What you don’t know you know may not be conscious—but it’s still most of what you know.

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