U.S. patent number 3,884,218 [Application Number 05/076,923] was granted by the patent office on 1975-05-20 for method of inducing and maintaining various stages of sleep in the human being.
This patent grant is currently assigned to Monroe Industries, Inc.. Invention is credited to Robert A. Monroe.
United States Patent |
3,884,218 |
Monroe |
May 20, 1975 |
Method of inducing and maintaining various stages of sleep in the
human being
Abstract
A method of inducing sleep in a human being wherein an audio
signal is generated comprising a familiar pleasing repetitive sound
modulated by an EEG sleep pattern. The volume of the audio signal
is adjusted to overcome the ambient noise and a subject can select
a familiar repetitive sound most pleasing to himself.
Inventors: |
Monroe; Robert A.
(Charlottesville, VA) |
Assignee: |
Monroe Industries, Inc.
(Charlottesville, VA)
|
Family
ID: |
22135011 |
Appl.
No.: |
05/076,923 |
Filed: |
September 30, 1970 |
Current U.S.
Class: |
600/28 |
Current CPC
Class: |
A61B
5/369 (20210101); A61M 21/00 (20130101); A61M
2021/0027 (20130101) |
Current International
Class: |
A61B
5/0476 (20060101); A61M 21/00 (20060101); A61b
019/00 () |
Field of
Search: |
;128/1C,2.1B,422 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
211,752 |
|
Apr 1968 |
|
SU |
|
1,165,541 |
|
Oct 1969 |
|
GB |
|
1,183,607 |
|
Dec 1964 |
|
DT |
|
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Sughrue, Rothwell, Mion, Zinn &
Macpeak
Claims
What is claimed is:
1. A method of inducing sleep in a human being, comprising the
steps of:
a. generating an audio signal representing a familiar, repetitive,
pleasing sound;
b. generating a signal approximating a human EEG signal waveshape
characteristic of a state of sleep;
c. amplitude modulating the audio signal with the EEG signal to
produce an output signal; and
d. producing an audible sound signal from the output signal for
listening by a human being.
2. The method of claim 1 further comprising the step of setting the
level of the audible sound signal above the ambient noise
level.
3. A method of inducing sleep comprising:
a. generating an EEG sleep pattern signal;
b. generating one of a plurality of signals;
c. modulating the one of a plurality of signals with the EEG sleep
pattern signal;
d. generating an audio signal from the modulated signal;
e. raising the audible level of the signal above the ambient noise
level of the environment; and
f. setting a timing device to automatically turn off the audio
signal after a predetermined time.
4. The method of claim 3 wherein the plurality of signals is
predetermined based upon the environment to which an individual is
accustomed.
5. The method of claim 4 wherein the EEG sleep pattern signals are
predetermined signals which have the same waveshape as the EEG
patterns generated by sleeping individuals.
6. The method of claim 3 wherein the step of selecting one of the
plurality of audio signals comprises an individual listening to
seven signals and deciding which signal is the most pleasing to
him.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of inducing sleep in a human
being, and more particularly, to a method of inducing sleep by the
generation of audio signals which are produced by the modulation of
familiar repetitive noises with electroencephalographic (EEG) sleep
patterns.
2. Description of the Prior Art
The use of audio generators to induce sleep is well known in the
prior art, as exemplified by U.S. Pat. Nos. 2,711,165 and
3,384,074. The audio signals used include pleasing and harmonious
steady sounds or vibrations, fixed frequency signals which are
cyclicly varied as to amplitude, and repetitive sounds such as the
falling of rain on a roof and the sighing wind through the
trees.
The prior art also discloses, in U.S. Pat. No. 3,304,095, a method
for inducing sleep by the generation of an audible or tactual
signal which is related to the physiological processes of heartbeat
and respiration. In this method, the pitch and amplitude of a
pleasing audio signal are varied at a rate somewhat slower than
either the rate of heartbeat or respiration. The heartbeat and
respiration will tend to synchronize with the audio signal thereby
lowering the heartbeat and respiration rate and inducing sleep.
SUMMARY OF THE INVENTION
The present invention comprises a method for inducing sleep wherein
familiar, repetitive, pleasing sounds are modulated by
predetermined EEG sleep signals to produce an audio signal which
induces various stages of sleep.
It has been found through the use of an EEG that various patterns
of electrical activity are associated with different states of
consciousness. There are two primary states, waking and sleeping.
Within the waking state, there are various degrees of alertness
ranging from frantichyperalertness through relaxed attentiveness to
drowsiness. There are also several stages of sleep ranging from a
light to deep. All of the various states of alertness and sleep
have EEG patterns which are characteristic of the state. These
patterns tend to be basically similar for all normal human beings.
It is well known in the prior art, as set forth above, that
familiar, repetitive, pleasing sounds tend to produce drowsiness
and sleep in an individual. In the method of this invention,
however, the pleasing sounds are combined with the EEG sleep
patterns by modulating the former with the latter. The audio signal
thereby produced has been found to be a quick and efficient sleep
inducing signal. In the method of this invention, the individual
has the opportunity of selecting a signal most pleasing to himself
for inducing sleep, and furthermore, he may determine the level of
the sleep inducing signal in order to overcome ambient noise
conditions.
In addition, the subject may time the sleep inducing signal such
that upon completion of a predetermined time period the signal will
stop and, he will drift back to wakefulness.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a typical human EEG pattern of awakeness with eyes
open.
FIG. 2 is an EEG pattern of awakeness with eyes closed.
FIG. 3 is an EEG pattern of drowsiness.
FIG. 4 is an EEG pattern of descending stage 1 sleep.
FIG. 5 is an EEG pattern of stage 2 sleep.
FIG. 6 is an EEG pattern of stage 2 sleep with sleep spindles.
FIG. 7 is an EEG sleep pattern of stage 3 sleep.
FIG. 8 is an EEG sleep pattern of stage 4 sleep.
DESCRIPTION OF THE PREFERRED METHOD
An electroencephalogram (EEG) is a device for measuring the
fluctuation of electrical potentials due to the electrical activity
of the brain. It has been found, through the use of the EEG, that
various patterns are generated during different states of
consciousness of the human being. This is the subject of the book
Electroencephalography: A Symposium In Its Various Aspects, by Hill
and Park. There are two primary states of consciousness, waking and
sleeping. Within the waking state, there are various degrees of
alertness ranging from frantic hyperalertness to drowsiness.
Extreme alertness is associated with a low voltage, generally fast
and irregular, of 10 to 20 microvolts amplitude and frequencies
ranging from 10 to 40 cycles per second. Relaxed alertness is
accompanied by an alpha rhythm, which is a regular sinusoidal
rhythm with a frequency between 8 to 13 cps. As the state of
consciousness changes from relaxed alertness to drowsiness, the
alpha rhythm breaks up and tends to become less and less
frequent.
The first stage of sleep or state 1 has an EEG pattern, as shown in
FIG. 4, which consists of an irregular mixture of theta waves which
are low in amplitude with a frequency of 4 to 8 cps, occasional
alpha waves, and irregularly occurring alphoid waves which are
similar to alpha waves but have a frequency of 1 to 2 cps lower
than the alpha wave.
An individual progresses from stage 1 sleep to stage 2 sleep, the
EEG pattern of which is shown in FIG. 5. The stage 2 pattern is
similar to stage 1 except that sleep spindles begin to appear. The
spindles are short bursts of waves at a frequency of about 14 cps.
They start at low amplitude and build up very rapidly to an
amplitude of 30 or 40 microvolts and then quickly taper off.
The individual then passes into stage 3 sleep, the EEG pattern of
which is shown in FIG. 7. Stage 3 sleep is characterized by the
appearance of delta waves which are waves of an amplitude of
approximately 100 microvolts or more and a frequency of 1 cps.
Stage 4 sleep which follows stage 3 sleep is characterized by a
preponderance of delta waves as opposed to the occasional delta
waves of stage 3 sleep. In sleep stages 3 and 4, the spindles and
irregular theta waves appearing in stage 2 sleep still appear.
Stages 1 through 4 were initially conceived of as comprising a
continuum from "light" to "deep" sleep, but many other measures of
the depth of sleep contradict this ordering. Stage 1 sleep
occurring later in the night seems to have very distinct
characteristics which make it a distinct kind of sleep, while
stages 2, 3 and 4 do seem to comprise a depth continuum in a second
kind of sleep.
Stage 1 EEG sleep periods later in the night are accompanied by
binocularly synchronous rapid eye movements (REMs), highly variable
heart rate and breathing, and an inhibition of nerve transmission
to the muscles.
If subjects are awakened from the two types of sleep and asked to
report what they have been experiencing, the reports may be
classified into two rather distinct types. One type - awakenings
from stage 1 sleep or shortly (within, roughly 10-15 minutes) after
stage 1 sleep has changed to nonstage 1 sleep - possesses the
characteristics traditionally associated with the experience of
dreaming. Reports from nonstage-1 sleep seem more like "thinking"
and are generally called thinking by the subjects (these same
subjects generally refer to their stage 1 experiences as dreams).
The psychological differences reported so far are quantitative,
rather than being completely dichotomous, but generally give the
impression of distinct types of experiences.
Stage 1 sleep is almost always accompanied by REMs, and the
evidence is very convincing that these are closely associated with
the content of the dream, if not actual scanning movements of the
dream imagery. Such REMs have not been reported in non-stage 1
sleep, although there are some slow, rolling movements of the
eyes.
For a normal subject, stage 1 dreaming and non-stage 1 sleep
alternate in a regular, cyclic fashion, the sleep-dream cycle. As a
subject falls asleep, there is generally a brief period (a few
seconds to a minute or two) of stage 1, without REMs, but subjects'
reports indicate that this is a period of hypnagogic imagery rather
than typical dreaming. At approximately 90 minute intervals
throughout the night there are periods of stage 1 dreaming, each
dream period generally being longer than the preceding one. The
first stage 1 period may last for 10 minutes; the fourth or fifth
may last as long as 50 minutes. Altogether, stage 1 dreaming
occupies between 20 and 30% of the total sleep time of most young
adults, spread over 3 to 6 stage 1 periods. While the exact
percentage of dream time and the number of cycles vary from subject
to subject, for a given subject the sleep-dream cycle is generally
quite stable from night to night.
It is well known that the human body will respond to several
sensory perceptions to induce sleep. However, the aural sense organ
is the only one which continues to function not only during
relaxation and drowsiness but also into the first three stages of
sleep as well. Therefore, the induction of sleep by aural means is
the most practical method of inducing controlled sleep.
It has been found that familiar repetitive sounds tend to produce
drowsiness and sleep. Conversely, the lack of these sounds tends to
produce alertness and wakefulness. The sounds which effect a
particular individual, because they must be familiar sounds, are
dependent upon the environment of that individual. In other words,
a city dweller may sleep with the steady rumble of traffic but he
might find the sound of crickets to be so noisy that he cannot
sleep. Investigation has shown that each individual is receptive to
a specific sound pattern and these patterns are the product of his
environmental conditioning. Some of the more common familiar
repetitive sounds which tend to induce sleep are rain on a roof,
machinery hum, gentle wind, ocean surf, breathing, heartbeat, the
human voice when noncommunicative or a steady 500 cycle hum.
Wakefulness is produced by such warning signals as auto horns,
alarms, baby cries, etc. Each individual, therefore, has a pattern
of response to various sounds. This pattern has been labeled his
sound condition index (SCI).
The cultural environment of humans has tended to standardize the
SCI to some degree for the various environments which groups of
people live in. For instance, the SCI for people living in a large
city would tend to be approximately the same as would the SCI for
people living out in the country.
In the preferred method of this invention, an audio generator is
placed near the bedside of an individual desiring to have sleep
induced. The generator has a capability of providing at least seven
basic sound patterns. These patterns are in accordance with the SCI
of the individual. Typically, the seven basic sounds for a person
living in an urban environment would be sounds of rain on a roof,
gentle wind, waves upon a beach, slow breathing, machinery hum, the
sound of a non-communicative human voice and a steady 500 cycle
hum. An individual, by listening to each of the seven sounds picks
the sound which would be most pleasing to him in order to induce
the sleep.
The sound generated by the audio generator is the pleasing
repetitive sound, as set forth above, amplitude modulated by the
stage 3 and 4 EEG sleep pattern. The amplitude of the pleasing
sound is confined to an envelope of the EEG sleep pattern. In other
words, the familiar repetitive sound is modulated by a wave of
theta sleep spindles and delta rhythms which are found in the EEG
pattern during stage 3 and 4 sleep. It should be noted that EEG
sleep pattern is not an EEG signal but a signal having the same
wave shape as an EEG signal. This sound rapidly produces stage 1
sleep followed by stage 2, 3 and 4 sleep in most individuals. It
has been found through experimentation that the results achieved by
inducing sleep with a signal synthesized by modulating a pleasant
signal with an EEG sleep pattern are several magnitudes higher than
induction of sleep by use of a pleasant sound only.
The apparatus for generating the familiar repetitive signal and the
EEG sleep pattern signal, as well as the apparatus for modulating
the former with the latter, may be any standard signal generators
and modulators which are well known in the signal generating
art.
One of the primary requirements of this method is that the sound
produced by the audio generator be sufficient to mask all of the
ambient noise in the environment of the individual. This is
effected by the individual raising the volume of the audio
generator until it is at a level above the ambient noise level of
the surroundings.
It has been found that sleep can be maintained by maintaining the
presence of the audio signal and that awakeness may be induced by
stopping the audio generator. Therefore, an individual may
determine the time which he sleeps by setting a timer which will
automatically turn off the sound generator and thereby return him
to a state of consciousness.
While the invention has been particularly shown and described with
reference to the preferred embodiments thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and the scope of the invention.
* * * * *