Study:
Human Hands Emit Light
By Jennifer Viegas, Discovery News
Sept.
6, 2005 — Human hands glow, but fingernails release
the most light, according to a recent study that found all parts
of the hand emit detectable levels of light.
The findings
support prior research that suggested most living things, including
plants, release light. Since disease and illness appear to affect
the strength and pattern of the glow, the discovery might lead
to less-invasive ways of diagnosing patients.
Mitsuo
Hiramatsu, a scientist at the Central Research Laboratory at
Hamamatsu Photonics in Japan, who led the research, told Discovery
News that the hands are not the only parts of the body that
shine light by releasing photons, or tiny, energized increments
of light.
"Not
only the hands, but also the forehead and bottoms of our feet
emit photons," Hiramatsu said, and added that
in terms of hands "the presence of photons means
that our hands are producing light all of the time."
The light
is invisible to the naked eye, so Hiramatsu and his team used
a powerful photon counter to "see"it.
The detector
found that fingernails release 60 photons, fingers release 40
and the palms are the dimmest of all, with 20 photons measured.
The findings
are published in the current Journal of Photochemistry and Photobiology
B: Biology.
Hiramatsu
is not certain why fingernails light up more than the other
parts of the hand, but he said, "It may be because
of the optical window property of fingernails,"
meaning that the fingernail works somewhat like a prism to scatter
light.
To find
out what might be creating the light in the first place, he
and colleague Kimitsugu Nakamura had test subjects hold plastic
bottles full of hot or cold water before their hand photons
were measured. The researchers also pumped nitrogen or oxygen
gas into the dark box where the individuals placed their hands
as they were being analyzed.
Warm temperatures
increased the release of photons, as did the introduction of
oxygen. Rubbing mineral oil over the hands also heightened light
levels.
Based on
those results, the scientists theorize the light "is
a kind of chemiluminescence," a luminescence based
on chemical reactions, such as those that make fireflies glow.
The researchers believe 40 percent of the light results from
the chemical reaction that constantly occurs as our hand skin
reacts with oxygen.
Since mineral
oil, which permeates into the skin, heightens the light, they
also now think 60 percent of the glow may result from chemical
reactions that take place inside the skin.
Fritz-Albert
Popp, a leading world expert on biologically related photons
at The International Institute of Biophysics in Germany, agrees
with the findings and was not surprised by them.
Popp told
Discovery News, "One may find clear correlations
to kind and degree (type and severity) of diseases."
Popp and
his team believe the light from the forehead and the hands pulses
out with the same basic rhythms, but that these pulses become
irregular in unhealthy people. A study he conducted on a muscular
sclerosis patient seemed to validate the theory.
Both he
and Hiramatsu hope future studies will reveal more about human
photon emissions, which could lead to medical diagnosis applications.
