Honey-Bee wrote:
How can I enter the Twilight Zone?
Enter the Twilight Zone: the Hypnagogic State
On the edge of sleep, you may enter hypnagogia, a state of freewheeling
thoughts and sometimes hallucinations.
Hypnagogia, or the hypnagogic state, is a brief period of altered consciousness
that occurs between wakefulness and sleep, typically as people “doze
off” on their way to normal sleep. During this period, thoughts can become
loosely associated, whimsical, and even bizarre. Hallucinations are very
common and may take the form of flashes of lights or colors, sounds, voices
(hearing your own name being called is quite common), faces, or fully
formed pictures. Mental imagery may become particularly vivid and fantastical,
and some people may experience synaesthesia, in which experiences in
one sense are experienced in another—sounds, for example, may be experienced
as visual phenomena.
It is a normal stage of sleep and most people experience it to some degree,
although it may go unnoticed or be very brief or quite subdued in some people.
It is possible, however, to be more aware of the hypnagogic state as it
occurs and to experience the effects of the brain’s transition into sleep more
fully.
In Action
Although there is no guaranteed technique to extend or intensify the hypnagogic
state, sometimes it can be enough to simply make a conscious effort to
be aware of any changes in consciousness as you relax and drop off, if practiced
regularly. Trying to visualize or imagine moving objects and scenes, or
passively noting any visual phenomena during this period might allow you
to notice any changes that take place. Extended periods of light sleep seem
more likely to produce noticeable hypnagogia, so being very tired may mean
you enter deep sleep too quickly. For this reason, afternoon dozing works
well for some.
Some experimenters have tried to extend or induce hypnagogia by using
light arousal techniques to prevent a quick transition into deep sleep. A
microphone and speaker were used in one study to feed the sound of breathing
back to the sleeper. Another method is the use of “repeat alarm clocks”
(like the snooze function on many modern alarm clocks)—on entering sleep,
subjects are required to try and maintain enough awareness to press a key
every 5 minutes; otherwise, a soft alarm sounds and rouses them.
Try this yourself on public transport. Because of the low background noise
and occasional external prompting, if you manage to fall asleep, dozing on
buses and trains can often lead to striking hypnagogic states. In spite of this,
this is not always the most practical technique, as you can sometimes end up
having to explore more than your own consciousness if you miss your stop.
How It Works
Very little research has been done on brain function during the hypnagogic
state, partly because conducting psychology experiments with semiconscious
people is difficult at the best of times and partly because many of the
neuroimaging technologies are not very soporific. fMRI (“Functional Magnetic
Resonance Imaging: the State of the Art” [Hack #4]) scanning tends to be
noisy and PET scanning (“Positron Emission Tomography: Measuring Activity
Indirectly with PET” [Hack #3]) often involves having a drip inserted into a
vein to inject radioactive tracer into the bloodstream—hardly the most
relaxing of experiences. As a result, most of the research has been done with
EEG (electroencephalogram) readings (“Electroencephalogram: Getting the
Big Picture with EEGs” [Hack #2]) that involve using small scalp electrodes to
read electrical activity from the brain.
Hideki Tanaka and colleagues [1] used EEG during sleep onset and discovered
that the brain does not decrease its activity evenly across all areas when
entering sleep. A form of alpha wave activity (electrical signals in the frequency
range of 8–12 Hz that are linked to relaxed states) spreads from the
front of the brain to the other areas before fading away. The frontal cortex is
associated with attention (among other things), and it may be that the hypnagogic
state results from the progressive defocusing of attention. This could
cause a reduction in normal perception filtering, resulting in loosely connected
thoughts and unusual experiences.
Electroencephalography (EEG) measures electrical activity
from the brain, through small electrodes attached to the
skull. The electrical signals are generated by neurons and the
amount of synchronous neural activity results in characteristic
EEG waveforms. Beta activity (above 14 Hz) is usually
linked to high levels of mental effort and cortical activation,
characteristic of the waking EEG. As mental activation
decreases and sleepiness appears, both alpha (8–13 Hz) and
theta (4–7 Hz) activity become more prominent. Delta activity
(activity below 4 Hz) is associated with deep, “slow-wave” sleep.
Some scientists have argued that the hypnagogic state is not necessarily
sleep-related and may be the result of a reduction in meaningful perceptual
information, perhaps leading to defocused attention or other similar effects.
A study published in 2002 [2] aimed to test this by comparing hypnagogic
states with a condition in which awake participants were fed unstructured
sensory information in the form of white noise and diffuse white light. The
researchers used EEG recordings and found that, although participants in
both conditions reported unusual visual experiences, the pattern of brain
activation were quite different, suggesting that hypnagogia is more than just
the result of relaxation and lack of structured sensory input.
One problem with recording electrical activity from the scalp is that activity
from structures that lie deep in the brain may not be detected. This means
we could be missing important information when it comes to understanding
what happens as we slip from consciousness into sleep, and even back
again into wakefulness (known as the hypnopompic state)—particularly as
deep structures (such as the brain stem, pons, thalamus, and hypothalamus)
are known to be crucial in initiating and regulating sleep.
An ingenious study published in Science did manage to investigate the role
of some of the deeper brain structures in hypnagogia [3], specifically the
medial temporal lobes, which are particularly linked to memory function.
The researchers asked five patients who had suffered medial temporal lobe
damage to play several hours of Tetris. Damage to this area of the brain
often causes amnesia, and the patients in this study had little conscious
memory for more than a few minutes at a time. On one evening, some hours
after their last game, the players were woken up just as they started to doze
and were asked for their experiences. Although they had no conscious memory
of playing the game, all of the patients mentioned images of falling,
rotating Tetris blocks. This has given us some strong evidence that the hypnagogic
state may be due (at least in part) to unconscious memories appearing
as unusual hypnagogic experiences.
In Real Life
Many authors and artists have been fascinated by this state and have tried to
extend or use it to explore ideas or gain inspiration. To name a couple, Robert
Louis Stevenson’s The Strange Case of Dr. Jekyll and Mr. Hyde and many
of Paul Klee’s paintings were reportedly inspired by hypnagogic experiences.
—Vaughan Bell
(
how do you like
that
?!!)
Now, I want to know....
why is cargo transported on a ship and not a car?
)
It took like ten minutes every moring to sort out what was real.
