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Review Article · Übersichtsarbeit
Forsch Komplementärmed Klass Naturheilkd 2005;12:77–83
Published online: March 7, 2005
DOI: 10.1159/000083763
Prof. Dr. Roeland Van Wijk
Koppelsedijk 1a
4191 LC Geldermalsen, The Netherlands
Tel. +31 345 570080, Fax 570110
E-mail roeland_van_wijk@meluna.nl
© 2005 S. Karger GmbH, Freiburg
Accessible online at:
www.karger.com/fkm
Fax +49 761 4 52 07 14
E-mail Information@Karger.de
www.karger.com
An Introduction to Human Biophoton Emission
Roeland Van Wijk
a, b
Eduard P.A. Van Wijk
b
a
Utrecht University, The Netherlands
b
International Institute of Biophysics, Neuss, Germany
Key Words
Ultraweak photon emission ⋅ Biophotons ⋅ Skin ⋅ Consciousness ⋅
Acupuncture
Summary
Background: Biophoton emission is the spontaneous emission of
ultraweak light emanating from all living systems, including man.
The emission is linked to the endogenous production of excited
states within the living system. The detection and characterisation
of human biophoton emission has led to suggestions that it has po-
tential future applications in medicine. Objectives: An overview is
presented of studies on ultraweak photon emission (UPE, biopho-
tons) from the human whole body. Methods: Electronic searches of
Medline, PsychLit, PubMed and references lists of relevant review
articles and books were used to establish the literature database.
Articles were then analysed for their main experimental setup and
results. Results: The, mostly, single case studies have resulted in a
collection of observations. The collection presents information on
the following fields of research: (1) influence of biological rhythms,
age, and gender on emission, (2) the intensity of emission and its
left-right symmetry in health and disease, (3) emission from the
perspective of Traditional Chinese and Korean Medicine, (4) emis-
sion in different consciousness studies, (5) procedures for analysis
of the photon signal from hands, (6) detection of peroxidative
processes in the skin. Of each article the main findings are present-
ed in a qualitative manner, quantitative data are presented where
useful, and the technological or methodological limitations are dis-
cussed. Conclusion: Photon emission recording techniques have
reached a stage that allows resolution of the signal in time and
space. The published material is presented and includes aspects
like spatial resolution of intensity, its relation to health and disease,
the aspect of colour, and methods for analysis of the photon signal.
The limited number of studies only allows first conclusions about
the implications and significance of biophotons in relation to health
and disease, or to mental states, or acupuncture. However, with
the present data we consider that further research in the field is
justified.
Schlüsselwörter
Ultraschwache Lichtstrahlung ⋅ Biophotonen ⋅ Haut ⋅ Bewusstsein ⋅
Akupunktur
Zusammenfassung
Hintergrund: Die Abstrahlung von Biophotonen ist eine spontane
ultraschwache Lichtstrahlung, die von allen lebenden Systemen
ausgeht, auch vom Menschen. Diese Strahlung hängt mit der en-
dogenen Erzeugung erregter Zustände im lebenden System zusam-
men. Die Entdeckung und genauere Charakterisierung der mensch-
lichen Biophotonenstrahlung hat zur Annahme geführt, dass es
dafür zukünftige medizinische Anwendungen geben könnte. Ziel-
setzung: Die Arbeit stellt einen Überblick dar über Studien zur ultra-
schwachen Photonenstrahlung (Biophotonen) des menschlichen
Körpers. Methode: Elektronische Literatursuche in Medline, Psych-
Lit, PubMed und Handsuche der Literaturverzeichnisse relevanter
Überblicksartikel und Bücher wurden benutzt, um die Literaturbasis
herzustellen. Einzelne Artikel wurden anschließend auf ihr experi-
mentelles Design und ihre Ergebnisse hin analysiert. Ergebnisse:
Die meisten Studien waren Einzelfallbeobachtungen und resultier-
ten in einer Sammlung von Beobachtungen. Der Überblick präsen-
tiert Informationen zu folgenden Forschungsgebieten: (1) Einfluss
biologischer Rhythmen, des Alters und des Geschlechts auf die
Biophotonenemission, (2) Intensität der Emission und Rechts-links-
Asymmetrie oder -Symmetrie in Gesundheit und Krankheit, (3) Bio-
photonenstrahlung aus der Perspektive der Traditionellen Chinesi-
schen und Koreanischen Medizin, (4) Biophotonenstrahlung in ver-
schiedenen Studien zur Bewusstseinsforschung, (5) Vorgehenswei-
sen zur Analyse des Photonensignals gemessen an den Händen, (6)
Entdeckung peroxidativer Prozesse in der Haut. Die Hauptergeb-
nisse jeder Arbeit werden qualitativ präsentiert, quantitative Daten
werden dargestellt, wo sinnvoll und nützlich. Die technologischen
und methodischen Begrenzungen werden diskutiert. Schlussfolge-
rung: Die Technik zur Erfassung der Biophotonenemission hat eine
Stufe erreicht, die eine gute Auflösung des Signals in Zeit und
Raum erlaubt. Die publizierte Literatur wird zusammengefasst und
enthält Informationen über Aspekte wie räumliche Auflösung der
Intensität, Beziehung der Strahlung zu Gesundheit und Krankheit,
Aspekte der Farbe bzw. Wellenlänge der Strahlung und Methoden
zur Analyse des Photonensignals. Die begrenzte Studienzahl erlaubt
jedoch nur erste Schlussfolgerungen über die Implikationen und
Reichweite der Biophotonen in Bezug auf Gesundheit und Krank-
heit, in Bezug auf Bewusstseinszustände oder in Bezug auf Anwen-
dungen wie Akupunktur. Auf jeden Fall sind wir der Meinung, dass
der gegenwärtige Forschungsstand weitere Forschung auf dem Ge-
biet rechtfertigt.
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Introduction
Research on human biophoton emission has appeared in the
literature since the 1970’s. Its nature is generally descriptive
and aetiology and the emission is generally understood to re-
flect the physiology of the human organism [1–6]. The ultra-
weak light emission originating spontaneously from living sys-
tems (UPE, ultraweak photon emission, biophoton emission,
or short: biophotons) ranges in intensity from a few to approx-
imately 10
2
photons / (s × cm
2
). It is thus not visible to the
naked eye and cannot be captured with commonly used opti-
cal detectors. The spectral range is 400–720 nm. The biological
origins and concrete mechanisms of this light emission are not
yet well understood. To study the role of biophoton emission
in living systems and in order to clarify its basic mechanisms,
highly sensitive measuring instruments are required that allow
non-invasive and non-destructive recording. Basically, three
types of systems have been developed to register UPE. Photo-
multipliers have evolved to extremely low-noise single photon
counting systems in which cooled photomultiplier tubes are
placed in a vacuum chamber to provide absolute stability of
the signal and maximum noise reduction. Photomultipliers
allow the study of biophoton emission utilising quantum sta-
tistical properties in actual living systems to clarify its basic
mechanisms. A second system utilised to study UPE also pro-
vides spectral analysis. For spectral characterisation a spectral
analyser system using a set of sharp cut-off, optical filters in
the wavelength range from ultraviolet (UV) to infrared (IR) is
commonly used. A third system to fundamentally characterise
UPE utilises a spatial distribution measurement or imaging of
biophoton emission. This is usually performed with ultra-sen-
sitive two-dimensional photon counting devices, as special
equipped charged-coupled devices [7].
This introductory review comprises two parts. The first part
presents historical aspects of biophoton research and touches
upon pilot work of many professional disciplines from the pe-
riod 1975–1995. The second part informs about additional re-
search and systematically presents information on human bio-
photon emission in relation to health and disease, the aspect
of colour, and methods for analysis of the photon signal. Of
each article, the main findings are presented in a qualitative
manner, quantitative data are presented where useful; tech-
nological or methodological limitations are discussed.
Method
This review concentrates on biophoton emission as extremely weak light
emanating from the whole and intact human body. It does not take into
account UPE from special internal organs or isolated body fluids. On the
basis of our own databases, we systematically compiled all citations found
in literature searches until end 2003: bibliographic database by electronic
search of Medline, PsychLit, PubMed, references lists of relevant review
articles [8, 9], books [10–12], and by contact with researchers in the field.
Each article was analysed for its main experimental question(s).
Historical Aspects
Early Attempts to Record the Human Envelope of Radiation
Research in human photon emission started at least three
decades ago. Early publications [13, 14] illustrate how fasci-
nated their authors were by previous reports of ‘an envelope
of radiation surrounding living organisms’. Utilising a DC-
photomultiplier, their studies produced a graphic record on a
XY recorder. The photomultiplier was mounted in a light-
tight darkroom scanned with a photomultiplier tube to
demonstrate that there were no leaks of light. The subjects
stood in front of the photomultiplier tube without clothes
from the waist up. The protocol avoided signals which resulted
from static electricity and fluorescence of dyes. The re-
searchers utilised a photocathode with a maximal sensitivity at
400 nm and almost zero activity at 650 nm, thus minimising
thermal effects. A major difficulty encountered in these early
experiments was the inherent internal noise produced by the
photomultiplier tube, which was of the same order of magni-
tude as the measured signal. To differentiate between signal
and noise, the signal was integrated and the average current
for the integration period was determined. The researchers re-
ported a statistically significant 11% increase of the signal
above background noise.
In this early research, experimental subjects were asked to
voluntarily increase emission intensity by breathing deeply
and by producing vibratory movements of the body. Only
some subjects were able to produce an increased signal, oth-
ers failed to do so. However, the increase of the signal did
coincide with the subjects’ attempts to increase their ‘energy
fields’. Controls did not produce an increase in the signal.
According to the researchers temperature changes could be
ruled out as the cause for signal increase. Different inani-
mate objects with emissions similar to that of the human
skin, and heated to varying temperatures between 30–90 °C,
did not increase the phototube output. Moreover, small fluc-
tuations in room temperature gave a negligible increase in
dark current.
Introduction of Sensitive Photomultipliers to Characterise
Human Biophoton Emission
Edwards and colleagues published a study on human body
photon emission in 1989 [15] and 1990 [16]. This study was
carried out as part of the Dove Project, in United Kingdom.
Its setup consisted of a photon detection system mounted in a
sealed housing with a quartz window, at a constant tempera-
ture of –23 °C. The mean dark noise in these experimental
conditions was around 60 counts per second (cps). The dark-
room was specially constructed, and the researchers took care
for the use of special materials in that room as well as regard-
ing subjects’ clothing. The authors recorded the temporal vari-
ation of the emission of the hand with measurements every
1.5 h over a 28-h period. Variation with time was observed,
but the data were not sufficient to allow any conclusion about
Forsch Komplementärmed Klass Naturheilkd
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An Introduction to Human Biophoton
Emission
79
diurnal periodicities. With respect to topographical variation
the count rate for five different body areas was recorded in
two subjects. Table 1 illustrates differences in count rate over
the body as well as between the foreheads and hands of both
subjects. These early findings already revealed that flat body
parts (abdomen, back, chest) emit at a lower intensity than
topologically complicated parts (head, hands). If a tourniquet
was applied around the upper arm, photon emission of the
palm was about 15% lower than otherwise. For spectral analy-
sis of hand emission coloured gelatin filters were interposed
between hand and photomultiplier. These filters divided the
visible spectrum into four bands, approximately correspond-
ing to the colours blue (410–495 nm), green (495–540 nm), yel-
low (540–570 nm) and red (570–650 nm). There was a clear
trend of increasing flux towards the red but due to temporal
variations the authors were not sure of the shape of the spec-
tral curve in more detail. In the wavelength region below
410 nm they were unable to reveal a significant departure
from the noise rate.
Introduction of Two-Dimensional Photon Counting
A special project on biophoton emission, the ‘Inaba Biopho-
ton Project’ was started by H. Inaba in Japan, in 1986. The
project was funded by the Exploratory Research for Ad-
vanced Technology (ERATO), a subsidiary of the Research
Development Corporation of Japan (presently, Japan Science
and Technology Corporation). Human biophoton emission
was investigated with two-dimensional photomultipliers in
order to record the two-dimensional pattern of UPE from the
human body surface. A two-dimensional image from the left
hand showed that photon emission was not uniform; it exhib-
ited a pattern with high intensity levels in the region of the
index and middle fingers and low intensity in the middle of
the palm [1, 17]. Photon emission could also be measured at
other regions of the body, but Inaba et al. limited their study
to human hands with the perspective of developing a simple
and easy non-invasive imaging technique for diagnostic pur-
poses (see section on Traditional Chinese and Korean Medi-
cine). In its early studies, the Japanese group had also posed
the question if hand photon emission was correlated with
body temperature [2]. With a small-size photomultiplier tube
intensity distributions of biophoton emission from the hand of
a healthy male subject were recorded. Data were correlated
with parallel recordings of the body surface temperature at
the same spots. No positive correlation between intensity dis-
tributions of biophoton emission and surface temperature was
found, although differences in their distribution existed, de-
pending on the individual subject.
Introduction of Large-Scale Scanning with a Moveable
Photomultiplier
In Germany, F.A. Popp and colleagues started pioneering re-
search in human biophoton emission in 1993 by building a
light-tight darkroom with black interior walls for the instal-
ment of a detector head that, by hanging on runners, could be
moved over the whole body of a subject lying on a bed under-
neath. The first cooled photomultiplier had a noise level of
about 20 cps and enabled registration of a real count rate of
3 cps in a measurement time of 30 min at a significance level
of 95%. The photon detector was moveable through a stepper
motor along 3 dimensions, and should allow the scanning of
the spontaneous photon emission. The largest scan area for a
two-dimensional image was 2 × 1 m [18]. Time of scanning de-
pended on several factors: time required to localise the pho-
ton detector, measuring time, and number of scanning points.
In the automatic programme, the time required to position the
detector was approximately 1 s, and the measurement time
could be adjusted between 10
–3
and 10
2
s. A high resolution
requires a large number of scanning points. On the other
hand, the low photon count rates require a long measurement
time in order to yield reliable values. As nobody can keep his
posture over several hours, a compromise had to be found be-
tween measuring time and resolution of a scan, in dependence
of the intensity of biophoton emission.
During the period from July 1994 to November 1995 the de-
vice was utilised to record biophoton emission in 80 healthy
and diseased subjects at a variety of body sites [18]. In each
subject, however, only few locations were recorded, and no
systematic measurement schedule was followed. The aim of
this initial research was to find features at specific body loca-
tions, which could characterise states of health and disease in
an integral manner.
It can be concluded from this historical overview that the res-
olution of human emission in time and space not only entails
extreme technical difficulties but also requires special tech-
niques for signal analysis. Notwithstanding these difficulties,
research has continued over the past 10 years, predominantly
in relation to health and disease.
Fields of Research on Human Biophoton Emission
What knowledge do studies on human photon emission pro-
vide? The documentation of experimental studies shows re-
cent progress in the investigations on the feasibility of medical
application of emission recordings.
Body location Subject 1 Subject 2
Abdomen 4.05 4.14
Lower back 6.60 4.87
Chest 5.42 5.63
Forehead 23.47 7.71
Hand 27.08 20.87
Table 1.
Topographical variation in photon emission (cps) in 2 subjects
as reported in early studies [15, 16]
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Biophoton Emission: Intensity and Left-Right Symmetry in
Diseased Patients
Several studies suggest that the intensity of photon emission
changes in a state of disease [1–3, 17–21]. In this respect, it is
necessary to distinguish between studies on wounding and
studies on patients with specific (chronic) diseases. The human
body shows photon emission from abnormal areas such as
wounds, sites of skin disease, and other injuries that affect the
skin surface [19]. Two-dimensional photon counting images
were taken of a scratch on the skin of the leg. About 30 h after
the injury, part of the scab was removed which caused body
fluid to exude from the affected part. At this site, an increased
emission could be imaged. An affected part of chronically dis-
eased skin that exuded body fluid also showed increased bio-
photon emission. In both cases, the very weak signal was ob-
tained in a 30-min observation time for photon counting.
Long-time observations have the merit of obtaining a higher
signal-to-noise ratio, however, a person normally cannot keep
still for a long time.
Several research groups presented data on a change in intensi-
ty of photon emission in the case of chronic diseases without
affection of the skin surface. The Japanese study [1, 2, 17] of
the two-dimensional pattern from the index and middle fin-
gers was used to differentiate hypothyroidism, a lower state of
metabolic activity than normal. Biophoton emission in pa-
tients with hypothyroidism was always less intense than nor-
mal. This lower emission was also found in patients whose thy-
roid glands had been removed. These results connect in a gen-
eral way the intensity of UPE with the basic metabolic rate.
In contrast, Cohen and Popp [18, 20, 21] reported of a multi-
ple sclerosis patient who emitted more biophotons than ordi-
nary healthy subjects. The authors introduced a second para-
meter for disease, e.g., percentage of difference in emission
between left and right hand. They suggested that in certain
diseases left-right symmetry of UPE from hands is broken.
Jung et al. [3] studied left-right symmetry of photon emission
from the palm and the dorsum of the hands of 7 Korean hemi-
paresis patients, and compared these data with similar data
from the hands of 20 self-reportedly healthy subjects. Mea-
surements were taken with two non-cooled photomultiplier
tubes inside a darkroom assembly specially fabricated to si-
multaneously measure biophoton emission from both hands
of one subject. According to the authors, the variation among
healthy people was not large; the largest deviation was about
25% of the average value. In the hemiparesis patients though,
the left and right differences of biophoton emission rates were
reported very large in 4 out of 7 patients, compared to the
20 healthy subjects both for the palm and the dorsum of the
hand. In the 3 other patients the differences were within nor-
mal range.
Biophoton Emission from Hands: Influence of Biological
Rhythms, Age, Gender
Since left-right asymmetry in photon emission intensity from
hands has been particularly investigated for the feasibility of
medical applications, other influences, e.g., of age, gender,
time of day and other biological rhythms, must also be taken
into account. Several studies have focused on these latter as-
pects. Edwards and colleagues [15, 16] studied daily variation
of the emission from the hands. In their study, measurements
were carried out every 1.5 h over a 28-h period, during which
the subject maintained usual eating and sleeping patterns.
Although variation with time was observed, the authors did
not find evidence for diurnal periodicities. Our group exam-
ined 29 body locations in 4 subjects for the emission in the
morning and afternoon [22]. Data demonstrate that the inten-
sity increased during the day depending on the subject as well
as the body location.
Cohen and Popp [20, 23] considered long-term periodicity in a
systematic study on photon emission from hands and fore-
head, using the moveable photon detector in the light-tight
darkroom. The authors examined both the palms of the hand
and the forehead of one subject, daily, over a period of
9 months. Recordings demonstrate a clear preference of left
and right hand correlation. Long-term biological rhythms of
spontaneous emission of that subject became evident with
Fourier analysis. The authors explained the rhythmic patterns
in terms of an oscillating body-photon field that follows defi-
nite rhythms and in which oscillations become stronger with
decreasing oscillation frequency. The phases of the oscillations
depended on the location within the body. Bilateral emission
from hands was higher in summer than in other seasons of the
year. A deviating pattern was observed for the forehead.
Bieske and colleagues [24] utilised a similar device to record
low-level emission from defined points of the hands and the
inside of the lower arm. From 3 subjects who took part in the
measurements series in summer and winter, it was concluded
that the subjects gave lower readings at all measurement
points in the winter series than in the summer series. The lat-
ter observation is in line with the observation by Cohen and
Popp [20, 23].
Influence of age on photon emission of hands has been re-
ported in two studies. Sauermann et al. [6] investigated two
age groups (n = 20, age 18–25 vs. n = 20, age 60–72). Sponta-
neous photon emission from the hands was increased in elder-
ly subjects. The authors correlated this observation with the
increased oxidative status of stratum corneum proteins in the
skin of elderly human skin. Also in the study by Choi et al.
[25] on 20 self-reportedly healthy subjects without any specific
disease the effect of age on biophoton emission from the
hands was examined. The subjects’ age ranged between 14 to
56 years (mean age 24 years). The authors distinguished three
age groups, in the teens, in the twenties, and over thirty, show-
ing 42.4 ± 3.31, 39.7 ± 4.15, 44.4 ± 7.55 cps for these age groups
(including a background of about 31 cps). They also analysed
their data for the 15 male and 5 female participants in their
study with respect to the influence of gender on biophoton
emission from the hands. The data showed biophoton emis-
sion of 41.4 ± 5.69 and 42.7 ± 3.75 for males and females, re-
spectively. The authors stated that the sample of subjects was
not sufficiently large, therefore data were only considered as
suggestive observations.
Biophoton Emission of Hands from the Perspective
of Traditional Chinese and Korean Medicine
Several studies on biophoton emission from the hands have
focused on special aspects of Traditional Chinese or Korean
Medicine. In these studies biophoton emission was discussed
in relation to the function of acupuncture meridians. The con-
ditions of the meridians are basic elements of Traditional Chi-
nese and Korean Medicine. According to this medical system,
diseases are caused by an unbalance of vital forces called Yin
and Yang, which for instance reflect left and right side of body,
respectively [3]. In their article on 7 hemiparesis patients, the
Korean researchers reported that left and right differences of
photon emission rates from the palm and the dorsum of the
hands were very large in 4 out of those 7 patients, compared to
20 healthy subjects [25]. They also reported that after
acupuncture treatment, the left and right difference in biopho-
ton emission was dramatically reduced: in each case the later-
al difference was normalised after the treatment. The Korean
research group also utilised a photomultiplier with an aper-
ture of 8 mm diameter, such that photons from point-like
sources could be detected [26]. Biophotons emitted from the
fingernails and fingerprints of 20 healthy subjects were mea-
sured. Significantly more emission was recorded from finger-
nails than fingerprints for each finger of each subject. Some
fingers emitted far stronger than others, and it depended on
the subject which finger emitted strongest.
In early studies by Inaba [27], attention was focused on pho-
ton emission from acupuncture points distributed on the hand
and finger. Emission intensity was compared to that from non-
acupuncture points. The author reported that around the fore-
arms and hands, photon emission tended to gradually de-
crease from the Shang-yang point to Ho-ku and then Chu-
chih acupuncture points, and that their intensities differed be-
tween right and left. The author also suggested that emission
from acupuncture points was normally higher than from non-
acupuncture points. Moreover, insertion of a needle [28] and
laser beam needle [29] into the acupuncture point enhanced
photon emission from other acupuncture points.
Yanagawa and colleagues [19] reported on a trial on the effect
of thermal stimulation by moxa, another method to influence
acupuncture points. In order to avoid a local painful burn,
moxa was selected and applied as sai-jyo on-kyu, i.e. warm
moxa on the navel, with an adjustable moxa height container.
After moxa treatment, in order to remove sweat or secretions
from the skin surface the moxa point was wiped with a tissue
paper that did not contain fluorescent substances. The authors
reported that photon emission from the moxa point was ob-
served. As a control condition, moxa treatment was carried
out on a special moxa mat made of cowhide, which showed no
effect on photon emission. The result was equal in control
measurement of a sample of sweat.
Human Biophoton Emission in Consciousness Studies
The role of consciousness in biophoton emission has been in-
vestigated in some studies. In an early study by Dobrin et al.
[13, 14] the experimental subjects’ intention to influence emis-
sion as compared to control subjects was subject of research.
The early equipment easily explains that this study could not
provide a clear answer.
Nakamura et al. [5] studied the influence of Qigong on
biophoton emission in 3 healthy men and 1 woman, aged
20–50 years. Photon emission was measured from the fingertip
with a cooled photomultiplier tube. Typically, the middle fin-
ger of the right hand was used. In one 50-year-old male, bio-
photon emission was increased during qi emission and de-
creased during relaxation. In the other subjects, however, no
such association between qi emission and biophoton emission
was observed.
Vekaria [30] investigated the influence of intention on photon
emission from the hand in 8 subjects – 6 females and 2 males.
If a person tried to intentionally change his or her photon
emission, the mean photon count decreased. Not all subjects
were able to influence photon emission with similar success.
Analyses revealed that there was an individual variation
among as well as within subjects. In another study, 3 subjects
were measured to check spectral characteristics of photon
emission using intention. The blue-yellow ratio increased
during the intention mode.
Recently, Van Wijk and colleagues [4] investigated the influ-
ence of meditation on photon emission from the hands and
forehead in 5 subjects. Data indicated that photon emission
changed after meditation. In one subject with high pre-medi-
tation values, photon emission decreased during meditation
and remained low in the post-meditation phase. Regarding the
other subjects, the study mostly demonstrated only a slight
decrease in photon emission, but commonly a decrease was
observed in the kurtosis and skewness values of the photon
count distribution.
Photon Counting Statistics of Biophotons from Hands
Because of the low intensity of biophoton signals, the question
is asked whether the biophoton signal is a result of random or
of coherent processes. Photon counting statistics on the distri-
bution of photons in a biophoton signal should provide an an-
swer to this question. In this respect, photon count distribu-
tion has been studied by two procedures.
The first procedure makes use of first and second moments.
The first moment gives n, the average rate of photon emis-
sion, while the second moment gives σ
2
, the square of stan-
dard deviation. These moments are combined to define the
Forsch Komplementärmed Klass Naturheilkd
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Forsch Komplementärmed Klass Naturheilkd
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parameter δ =(σ
2
–n)/n for testing randomness or coherence
of the signal. The value of δ is zero for Poisson distribution
and positive for thermal distribution. In addition, higher prob-
ability moments of photon emission are sometimes calculated.
This procedure was used for the analysis of the spontaneous
photon emission of several body locations [18] as well as for
biophoton signals emitted from the hands of 20 healthy sub-
jects and a few paralytic patients [31]. It was observed that the
higher probability moments of biophotons from healthy sub-
jects corresponded to Poisson distribution while those of para-
lytic persons revealed deviations from Poisson distribution
and seemed to approach geometrical distribution. The authors
explained these findings in terms of interrelations of the un-
derlying metabolic processes.
The second procedure makes use of the Fano factor F(T) that
quantifies the deviation from Poisson statistics as a function
of observation time T. F(T) as used by Vekaria [30] and
Kobayashi et al. [32] is defined as the variance of the number
of photons divided by the mean number of photons for a given
time window of length T. For a periodic (rhythmic) process,
the variance decreases and F approaches zero as the window
size is increased. In contrast, for a fractal process, F increases
as a power of the window size and may reach values >1.0. This
reflects the greater variance in photon counts with increasing
window size. The increase in variance occurs because rare
clusters of high and low photon counts are more apt to be
found the more data are collected. Such clustering has been
considered as characteristic of a fractal process [33, 34]. With-
out discussing it in detail, the authors concluded that photon
count statistics had a potential to be used as an indicator of
the healthy state, but that additional case studies were re-
quired to determine statistically significant diagnostic criteria.
Recently, Van Wijk et al. characterised photon emission from
the hands in the pre- and post-meditation phases by the Fano
factor [4]. Data indicated that the Fano factor time curve is
useful to quantify the effect of meditation on human photon
emission.
Application for Evaluation of Skin Oxidative Status
and Antioxidant Capacity
Sauermann et al. [6] reviewed applications of photon emission
recording since the 1980’s in studies on human skin that was
treated with UV, ultrasound, topical applications of peroxides,
and antioxidants. Most of the existing methods for evaluation
of skin oxidative status and antioxidant capacity are invasive
and require removal of the skin, its separation into its various
layers, homogenisation, and analysis of its antioxidants or its
oxidation products. It is obvious that such measurements can-
not be done on a large scale in humans. Instead, monitoring of
UPE directly on the skin has provided a unique technique for
routine non-invasive detection of peroxidative processes and
the effectiveness of antioxidants for human skin in vivo.
Experimental Setup and Future Questions
Protocol
The handling of subjects requires careful attention by the re-
searcher. It has been reported that illumination with (artifi-
cial) sunlight leads to a delayed luminescence, its kinetics,
however, is essentially unknown. It may last long, and has to
be carefully controlled. Other conditions that need to be con-
trolled are temperature, humidity, skin condition (creams and
lotions) and clothing of the subjects (e.g. photosensitisers in
laundry powder). Also, static electricity that may be caused
by friction may lead to spurious luminescence effects. Another
aspect is the recording time necessary to obtain reliable aver-
age values of the intensity. Only few studies [22] show primary
data on fluctuations in photon count time series. The origin of
such fluctuations has not been carefully analysed and needs
further characterisation.
Multi-Site Recording of Human Emission
Data shows that photon emission differs between subjects, be-
tween body locations, and in time. A more systematic ap-
proach is required to describe time-spatial aspects of human
biophoton emission. Also, the aspect of symmetry in emission
deserves special attention. Furthermore, a combination of the
techniques of 1- and 2-dimensional recording must be stimu-
lated to collect optimal information about biophoton emission
in time and space.
Recording of Colour Spectrum
The analysis of the spectral distribution of very weak intensi-
ties has limitations relative to equipment specifications [35].
Mostly, cut-off glass filters with high transmittances are
utilised to prevent loss of photons when recording very weak
emission. However, the comparison of colour spectrum over
the body remains difficult due to the low emission at certain
sites and the large differences between body sites. To find the
pitfalls in such studies, careful stepwise analysis of the spectra
of human body sites is required.
Body Position and Mental State
The tourniquet experiment has shown the importance of
blood flow and thus the positioning of the subject during long-
term recordings. Moreover, the present review suggests that
the subject’s state of consciousness must be taken into ac-
count. On both aspects – fixed positioning and mental state –
more data must be collected, in particular during long-term
recordings.
Photon Count Statistics in Human Biophoton Emission
Several procedures for statistical analyses of photon counts
have been applied on human biophoton emission data. In the
light of the coherency theory of photon emission [36–38], the
application of photon count statistics must be further promot-
ed. In summary, we believe that work on human biophoton
Forsch Komplementärmed Klass Naturheilkd
2005;12:77–83
An Introduction to Human Biophoton
Emission
83
emission deserves to be continued in order to better under-
stand the physiological implications of the present data, par-
ticularly regarding stress and disease [9, 39].
Conclusion
While weak photon emission from a variety of mammal tis-
sues has been previously reviewed [8–12], photon emission
from the intact human body has not been reviewed before.
Data are scarce and spread through the literature of the last
30 years. The limited number of studies observed does not
allow hard conclusions about the implications and significance
of biophotons in relation to health and disease, mental state,
or acupuncture. Still, the presented experimental data, make
clear that these aspects need attention in future research.
Among others our group will focus on some of these prob-
lems, the results are presented in separate publications [4, 22].
Acknowledgements
The authors wish to thank the Samueli Institute for Information Biology,
the Rockefeller-Samueli Center for Research in Mind-Body Energy, the
Fred Foundation, and the Foundation for Bioregulation Research for
financial support.
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