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Magnetic Therapy Research: For Sleep and Insomnia

12-month, double-blind clinical test of magnetic mattress pads

  • Out of 375 patients sleeping on the magnetic mattress pads, 80.27% reported positive results.
  • Over 70% of the experimental patients realized the effects within 5 days.
  • Benefits included significant reductions in back pain, neck & shoulder pain, leg pain, insomnia and fatigue.
  • No reported side effects.

16-week randomized, double-blind study of magnetic mattress pad use for Fibromyalgia

  • Sleeping on a magnetic mattress pad provides statistically significant and clinically relevant pain relief, sleep improvement, and improved physical functioning in subjects with fibromyalgia.
  • Subjects sleeping on the sham mattress pad experienced no significant changes.
  • No adverse reactions were noted in the experimental group.

6-month randomized, controlled trial of magnetic sleep pads for Fibromyalgia

  • Subjects sleeping on magnetic sleep pads reported statistically significant reductions in pain intensity compared to the two sham groups.
  • A greater reduction in the number of tender points, tender point intensity, and improvements in functional status were also reported in the magnet group, however these improvements were not statistically significant.

Full List of Study Abstracts:


Summary of a 12-month double-blind, clinical test of magnetic mattress pads.

Carried out by Sanikukal Hospital, Tokyo Communications Hospital and Kouseikai Suzuki Hospital, by Dr. Kazuo Shimodaira. 1990.

The mattress pads used in this study were typical full-size pads containing 124 permanent ferrite magnets with magnetic field strengths of 750-950 gauss each. The pads themselves were made of two sheets of felt with the magnets sandwiched between them. The felt sheets were then wrapped in a cloth cover. The total number of subjects of this double-blind clinical experiment was 431 (216 male, 215 female). 375 subjects were given the magnetic pads, 56 were given non-magnetic pads. None of the 431 subjects knew which pad they were sleeping on. Subjects selected for the experiment were those with chief complaints related to:

  • Neck and Shoulder pain
  • Back and Lower Back Pain
  • Back Pain (general)
  • Lower Limb Pain
  • Insomnia
  • Fatigue

To determine the presence of any side effects, blood pressure, hemoglobin, number of erythrocytes, and number of leukocytes were examined before and after the use of the mattress pads. Besides blood sedimentation, and TP, COL, ALP, GOT, GPT, Na, and K were also examined, as were functions of the kidneys, liver, pancreas, and the entire circulatory system.


Symptom Total Cases # of Positive % of Total # of No Results % of Total
Neck & Shoulder Pain 66 47 71.2% 19 28.8%
Lower Back Pain 76 61 80.3% 15 19.7%
General Back Pain 31 25 80.7% 6 19.3%
Lower Limb Pain 68 54 79.4% 14 20.6%
Insomnia 70 61 87.1% 9 12.9%
Fatigue 64 53 82.8% 11 17.2%

Out of 375 total subjects with symptoms:

  • 301 (80.27%) reported positive results.
  • 74 cases (19.73%) reported no results

Time of Response:

The percentage of subjects who realized the effect of the magnetic mattress pad within 3 days:

Neck & Shoulder Pain 46.9%
Back & Lower Back Pain 50.0%
Back Pain (general) 38.7%
Lower Limb Pain 54.4%
Insomnia 64.3%
Fatigue 57.8%

Out of 375 total subjects who slept on the magnetic mattress pads:

  • 200 (53.3%) realized the effects within 3 days.
  • Over 70% realized the effects within 5 days.

Testing for side effects was conducted at the conclusion of the experiment. Symptoms such as tinnitus, headache, hearing problems, visual disturbances, vertigo, palpitation, perceptive abnormality, motorial disturbance, fever, digestive disturbance, coetaneous symptoms, and other clinical symptoms to suggest any side effects were found to be totally absent. Extensive testing was also done before and after the experiment to check functions of kidneys liver, pancreas, blood pressure, and the circulatory system. No clinical symptoms were found to indicate any side effects whatsoever.


Dr. Shimodaira's conclusion of this year-long study conducted in 3 of Japan's foremost hospitals: "The magnetized health mattress pad is proved to be effective on neck and shoulder pain, back and lower back pain, back pain, lower limb pain, insomnia, and fatigue, and to have no side effects."

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Magnetic Mattress Pad Use in Patients with Fibromyalgia: a Randomized Double-blind Pilot Study.

Agatha P. Colbert, M.D.
Clinical Assistant Professor of Physical Medicine and Rehabilitation
Tufts University School of Medicine, Boston, MA 02111

Marko S Markov, Ph.D.
Department of Orthopedics
Mount Sinai School of Medicine, New York

Mandira Baneiji, M.A.
Research Assistant, Litterst & Associates, Newton, MA

Arthur A Pilla, Ph.D.
Department of Orthopedics, Mount Sinai School of Medicine, New York
Department of Biomedical Engineering, Columbia University, New York

OBJECTIVE: To determine if the chronic pain and sleep disturbances experienced by patients with fibromyalgia can be improved by sleeping on a magnetic mattress pad.

PATIENTS: Thirty-five female subjects diagnosed with fibromyalgia syndrome were recruited. Thirty met inclusion/exclusion criteria and entered the study. Twenty-five completed it. One was lost to follow-up. Three were withdrawn for protocol violations and one because of an intercurrent hospitalization.

INTERVENTION: Sleeping on an experimental (magnetized at a magnet surface field strength of 1100 +/- 50 Gauss and delivering 200-600 Gauss to the skin surface or a sham (non-magnetized) mattress pad over a 16 week period.

MAIN OUTCOME MEASURES: Visual Analog Scales (VAS) for global well-being, pain, sleep, fatigue and tiredness on awakening; Total Myalgic Score; Pain Distribution Drawings; and a modified Fibromyalgia Impact Questionnaire.

RESULTS: Subjects sleeping on the experimental mattress pad experienced a significant decrease in pain ~ <.05), fatigue ~<.006), total myalgic score ~ <.03), and pain distribution drawing (1) <.02). Additionally, these subjects showed significant improvement in reported sleep (p <.01) and physical functioning as evidenced from the modified Fibromyalgia Impact Questionnaire ~ <.04). Subjects sleeping on the sham mattress pad experienced no significant change in these same outcome measures. Subjects in both the control and experimental groups showed improvement in tiredness on wakening, demonstrating a placebo effect in this parameter. Neither group showed any effect on global wellbeing.

CONCLUSIONS: Sleeping on a magnetic mattress pad, with a magnet surface field strength of 1100 +/- 50 Gauss, delivering 200-600 Gauss at the skin surface provides statistically significant and clinically relevant pain relief and sleep improvement in subjects with fibromyalgia. No adverse reactions were noted during the 16-week trial period.

Journal of Back and Musculoskeletal Rehabilitation 13(1999) 19-31

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Static magnetic fields for treatment of fibromyalgia: a randomized controlled trial.

Alfano AP, Taylor AG, Foresman PA, Dunkl PR, McConnell GG, Conaway MR, Gillies GT.

Department of Physical Medicine and Rehabilitation, University of Virginia Health System, Charlottesville, USA.

OBJECTIVE: To test effectiveness of static magnetic fields of two different configurations, produced by magnetic sleep pads, as adjunctive therapies in decreasing patient pain perception and improving functional status in individuals with fibromyalgia.

DESIGN: Randomized, placebo-controlled, 6-month trial conducted from November 1997 through December 1998.

SETTING AND SUBJECTS: Adults who met the 1990 American College of Rheumatology criteria for fibromyalgia were recruited through clinical referral and media announcements and evaluated at a university-based clinic.

INTERVENTIONS: Subjects in Functional Pad A group used a pad for 6 months that provided whole-body exposure to a low, uniform static magnetic field of negative polarity. Subjects in the Functional Pad B group used a pad for 6 months that exposed them to a low static magnetic field that varied spatially and in polarity. Subjects in two Sham groups used pads that were identical in appearance and texture to the functional pads but contained inactive magnets; these groups were combined for analysis. Subjects in the Usual Care group continued with their established treatment regimens.

OUTCOME MEASURES: Primary outcomes were the change scores at 6 months in the following measures: functional status (Fibromyalgia Impact Questionnaire), pain intensity ratings, tender point count, and a tender point pain intensity score.

RESULTS: There was a significant difference among groups in pain intensity ratings (p = 0.03), with Functional Pad A group showing the greatest reduction from baseline at 6 months. All four groups showed a decline in number of tender points, but differences among the groups were not significant (p = 0.72). The functional pad groups showed the largest decline in total tender point pain intensity, but overall differences were not significant (p = 0.25). Improvement in functional status was greatest in the functional pad groups, but differences among groups were not significant (p = 0.23).

CONCLUSIONS: Although the functional pad groups showed improvements in functional status, pain intensity level, tender point count, and tender point intensity after 6 months of treatment, with the exception of pain intensity level these improvements did not differ significantly from changes in the Sham group or in the Usual Care group.

J Altern Complement Med 2001 Feb;7(1):53-64

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Sleep inducing effect of low energy emission therapy.

Reite M, Higgs L, Lebet JP, Barbault A, Rossel C, Kuster N, Dafni U, Amato D, Pasche B.

Department of Psychiatry, University of Colorado Health Sciences Center, Denver.

The sleep inducing effect of a 15 min treatment with either an active or an inactive Low Energy Emission Therapy (LEET) device emitting amplitude-modulated electromagnetic (EM) fields was investigated in a double-blind cross-over study performed on 52 healthy subjects. All subjects were exposed to both active and inactive LEET treatment sessions, with an interval of at least 1 week between the two sessions. LEET consists of 27.12 MHz amplitude-modulated (sine wave) EM fields emitted intrabuccally by means of an electrically conducting mouthpiece in direct contact with the oral mucosa. The estimated local peak SAR is less than 10 W/kg in the oral mucosa and 0.1 to 100 mW/kg in brain tissue. No appreciable sensation is experienced during treatment, and subjects are therefore unable to tell whether they are receiving an active or an inactive treatment. In this study the active treatment consisted of EM fields intermittently amplitude-modulated (sine wave) at 42.7 Hz for 3 s followed by a pause of 1 s during which no EM fields were emitted. During the inactive treatment no EM fields were emitted. Baseline EEGs were obtained and 15 min post-treatment EEGs were recorded and analyzed according to the Loomis classification. A significant decrease (paired t test) in sleep latency to stage B2 (-1.78 +/- 5.57 min, P = 0.013), and an increase in the total duration of stage B2 (1.15 +/- 2.47 min, P = 0.0008) were observed on active treatment as compared with inactive treatment.

Bioelectromagnetics. 1994;15(1):67-75.

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Static Magnetotherapy for the Treatment of Insomnia.

Shieh YY, Tsai FY.

Department of Radiological Sciences, School of Medicine, UC Irvine Medical Center, Orange, CA 92868, USA.

Magnets have been used for centuries to treat a number of physical disorders. The vast majority of research, however, on static magnet therapy for insomnia has been confined to the auricular type of therapy, with publications limited to Chinese journals. Most of these studies have depended on the subjective self-assessment of participants rather than objective scientific measurements. In this study, the authors report the positive preliminary results of insomnia treatment using pillows with embedded magnets, magnetic insoles and TriPhase bracelets. The analysis is based on objective actigraphic and polysomnographic data. A theory of accelerated transition from wakefulness to sleep is proposed to explain the process of insomnia relief through low-strength static magnetic fields. Analysis by functional Magnetic Resonance Imaging (fMRI) is used to further investigate the theory.

Int J Electron Healthc. 2008;4(3-4):339-49.

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Effects of low energy emission therapy in chronic psychophysiological insomnia.

Pasche B, Erman M, Hayduk R, Mitler MM, Reite M, Higgs L, Kuster N, Rossel C, Dafni U, Amato D, Barbault A, Lebet JP.

Symtonic USA, Inc., New York, New York 10162, USA.

The treatment of chronic psychophysiological insomnia presents a challenge that has not been met using currently available pharmacotherapy. Low energy emission therapy (LEET) has been developed as a potential alternative therapy for this disorder. LEET consists of amplitude-modulated electromagnetic fields delivered intrabuccally by means of an electrically conducting mouthpiece in direct contact with the oral mucosa. The effect of LEET on chronic psychophysiological insomnia was assessed with polysomnography (PSG) and sleep rating forms on a total of 106 patients at two different centers. Active or inactive LEET was administered for 20 minutes in late afternoon three times a week for a total of 12 treatments. Primary efficacy endpoints evaluating the results were changes from baseline in PSG-assessed total sleep time (TST) and sleep latency (SL). Secondary endpoints were changes in sleep efficiency (SE), sleep stages, and reports by the subjects of SL and TST. There was a significant increase in TST as assessed by PSG between baseline and post-treatment values for the active treatment group (76.0 +/- 11.1 minutes, p = 0.0001). The increase for the inactive treatment group was not statistically significant. The TST improvement was significantly greater for the active group when compared to the inactive group (adjusted for baseline TST; p = 0.020. R1 = 0.20). There was a significant decrease in SL as assessed by PSG between baseline and post-treatment values for the active treatment group (-21.6 +/- 5.9 minutes, p = 0.0006), whereas the decrease noted for the inactive treatment group was not statistically significant. The difference in SL decrease between the two treatment groups was marginally significant (adjusted for baseline SL and center, p = 0.068, R2 = 0.60). The number of sleep cycles per night increased by 30% after active treatment (p = 0.0001) but was unchanged following inactive treatment. Subjects did not experience rebound insomnia, and there were no significant side effects. The data presented in this report indicate that LEET administered for 20 minutes three times a week increased TST and reduced SL in chronic psychophysiological insomnia. LEET is safe and well tolerated and it effectively improved the sleep of chronic insomniacs given 12 treatments over a 4-week period by increasing the number of sleep cycles without altering the percentage of the various sleep stages during the night. The therapeutic action of LEET differs from that of currently available drug therapies in that the sleep pattern noted in insomniacs following LEET treatment more closely resembles nocturnal physiological sleep. This novel treatment may offer an attractive alternative therapy for chronic insomnia.

Sleep. 1996 May;19(4):327-36.

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Pulsed high-frequency electromagnetic field affects human sleep and sleep electroencephalogram.

Borbely AA, Huber R, Graf T, Fuchs B, Gallmann E, Achermann P.

Institute of Pharmacology and Toxicology, University of Zurich, Switzerland.

To investigate whether the electromagnetic field (EMF) emitted by digital radiotelephone handsets affects the brain, healthy, young subjects were exposed during an entire night-time sleep episode to an intermittent radiation schedule (900 MHz; maximum specific absorption rate 1 W/kg) consisting of alternating 15-min on-15-min off intervals. Compared with a control night with sham exposure, the amount of waking after sleep onset was reduced from 18 to 12 min. Spectral power of the electroencephalogram in non-rapid eye movement sleep was increased. The maximum rise occurred in the 10-11 Hz and 13.5-14 Hz bands during the initial part of sleep and then subsided. The results demonstrate that pulsed high-frequency EMF in the range of radiotelephones may promote sleep and modify the sleep EEG.

Neurosci Lett. 1999 Nov 19;275(3):207-10.

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The effects of natural and man-made electromagnetic fields on mood and behavior: the role of sleep disturbances.

Sher L.

Natural and man-made electromagnetic fields influence the mood and behavior of healthy and sick people. Considerable evidence suggests that electromagnetic fields affect sleep. The author suggests that electromagnetic field-induced changes in sleep may mediate the effects of electromagnetic fields on mood, behavior, and cognitive abilities. The author further suggests that the development of sleep abnormalities in persons exposed to artificial electromagnetic fields may predict the onset of a psychiatric disorder at a later time and that early intervention may prevent the onset of a psychiatric disease. Copyright 2000 Harcourt Publishers Ltd.

Med Hypotheses. 2000 Apr;54(4):630-3.

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Space environment, electromagnetic fields, and circadian rhythm.

Izumi R, Ishioka N, Mizuno K, Goka T.

Human space activity began in 1961. About 400 persons have gone to space since then, and about 70 of them have stayed more than 1 month. Circadian rhythm and sleep in space have been investigated several times, though the effect of longer stays in space has not been adequately clarified. Electromagnetic fields are different in the space environment, especially in deeper space missions, such as the Moon or Mars, but their effects on human health have rarely been studied. In this article, we summarize the current status of the International Space Station project, study circadian rhythm and sleep in space, investigate electromagnetic fields, and state the necessity for investigating this research field.

Biomed Pharmacother. 2001;55 Suppl 1:25s-31s.

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Modulation by ultralow intensity electromagnetic fields on pharmacologic effects of psychotropic drugs.

Shtemberg AS, Bazian AS, Shikhov SN, Cherniakov GM, Uzbekov MG.

National Research Center Institute of Medical and Biological Problems, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Research Institute of Psychiatry, Russian Ministry of Public Health, Moscow.

The ultralow-intensity electromagnetic fields (EMF, frequency of 4200, modulated by a quasistochastic signal in the range of 20-20,000 Hz, power density of 15 microW/cm2, specific body absorption rate up to 4.5 mJ/kg) potentiated the hypnogenic effect of hexenal. The exposure to the EMF shortened the time of falling asleep induced by this drug and increased sleep duration in rats. The exposure to the EMF also potentiated haloperidol catalepsy: it decreased the drug threshold dose and increased the catalepsy duration. The EMF influence on the haloperidol effects was of a prolonged character: it was manifest in a selected suppression of the emotional excitation in the open-field test within 24 hours after the exposure.

Zh Vyssh Nerv Deiat Im I P Pavlova. 2001 May-Jun;51(3):373-7.

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Impulse magnetic-field therapy for insomnia: a double-blind, placebo-controlled study.

Pelka RB, Jaenicke C, Gruenwald J.

Universitat der Bundeswehr Munchen Neubiberg/Munich, Germany.

This 4-week double-blind, placebo-controlled study assessed the efficacy of impulse magnetic-field therapy for insomnia. One hundred one patients were randomly assigned to either active treatment (n = 50) or placebo (n = 51) and allocated to one of three diagnostic groups: (1) sleep latency; (2) interrupted sleep; or (3) nightmares. Efficacy endpoints were intensity of sleep latency, frequency of interruptions, sleepiness after rising, daytime sleepiness, difficulty with concentration, and daytime headaches. In the active-treatment group, the values of all criteria were significantly lower at study end (P < .00001). The placebo group also showed significant symptomatic improvement (P < .05), but the differences between groups were highly significant (P < .00001). 70% (n = 34) of the patients given active treatment experienced substantial or even complete relief of their complaints; 24% (n = 12) reported clear improvement; 6% (n = 3) noted a slight improvement. Only one placebo patient (2%) had very clear relief; 49% (n = 23) reported slight or clear improvement; and 49% (n = 23) saw no change in their symptoms. No adverse effects of treatment were reported.

Adv Ther. 2001 Jul-Aug;18(4):174-80.

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The influences of extremely low frequency magnetic fields on clonidine-induced sleep in 2-day-old chicks.

Min YS, Jeong JH, Choi YM, Lee BC, Huh IH, Lee SY, Sohn UD.

Department of Pharmacology, College of Pharmacy, Chung Ang University, Seoul 156-756, Republic of Korea.

1. It has been shown that magnetic fields (MFs) affect a variety of biological effects in animal brains. There have been few experiments on the effects of MFs on sleep. Therefore, we investigated whether extremely low frequency (ELF) MFs affect the sleep induced by clonidine, a central alpha(2)-adrenoceptor agonist. Clonidine produced dose-related increase of the sleeping time and dose-related decrease of the onset time in 2-day-old chicks. 2. Exposure of chicks to MFs (5, 10, 20 G; for 3, 6, 9, 12 h) significantly increased the clonidine-induced sleep time as a direct function of intensity and duration of MF application. Clonidine reduced noradrenaline or tyrosine in the brain, an effect which was not further changed in animals exposed to MF. 3. To determine whether the gamma amino butyric acid A (GABA(A))/benzodiazepine (BZD) receptor system is involved in the decrease in clonidine-induced sleep caused by activation of central alpha(2)-adrenergic systems, we examined exposure of chicks to the effects of the BZD receptor antagonist flumazenil (0.5 mg kg(-1), i.p.) and GABA(A) antagonist bicuculline (0.1 mg kg-1, i.p.) on clonidine-induced sleep. Bicuculline and flumazenil inhibited the increase of clonidine-induced sleep time by MFs. Clonidine or MFs did not change GABA levels in the brain. 4. These results suggest that MFs can increase clonidine-induced sleep via a change of GABA(A) and BZD receptor system irrespective of the concentration of GABA or noradrenaline in the brain of 2-day-old chicks.

J Auton Pharmacol. 2001 Aug;21(4):197-203.

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Electromagnetic fields, such as those from mobile phones, alter regional cerebral blood flow and sleep and waking EEG.

Huber R, Treyer V, Borbely AA, Schuderer J, Gottselig JM, Landolt HP, Werth E, Berthold T, Kuster N, Buck A, Achermann P.

Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.

Usage of mobile phones is rapidly increasing, but there is limited data on the possible effects of electromagnetic field (EMF) exposure on brain physiology. We investigated the effect of EMF vs. sham control exposure on waking regional cerebral blood flow (rCBF) and on waking and sleep electroencephalogram (EEG) in humans. In Experiment 1, positron emission tomography (PET) scans were taken after unilateral head exposure to 30-min pulse-modulated 900 MHz electromagnetic field (pm-EMF). In Experiment 2, night-time sleep was polysomnographically recorded after EMF exposure. Pulse-modulated EMF exposure increased relative rCBF in the dorsolateral prefrontal cortex ipsilateral to exposure. Also, pm-EMF exposure enhanced EEG power in the alpha frequency range prior to sleep onset and in the spindle frequency range during stage 2 sleep. Exposure to EMF without pulse modulation did not enhance power in the waking or sleep EEG. We previously observed EMF effects on the sleep EEG (A. A. Borbely, R. Huber, T. Graf, B. Fuchs, E. Gallmann and P. Achermann. Neurosci. Lett., 1999, 275: 207-210; R. Huber, T. Graf, K. A. Cote, L. Wittmann, E. Gallmann, D. Matter, J. Schuderer, N. Kuster, A. A. Borbely, and P. Achermann. Neuroreport, 2000, 11: 3321-3325), but the basis for these effects was unknown. The present results show for the first time that (1) pm-EMF alters waking rCBF and (2) pulse modulation of EMF is necessary to induce waking and sleep EEG changes. Pulse-modulated EMF exposure may provide a new, non-invasive method for modifying brain function for experimental, diagnostic and therapeutic purposes.

J Sleep Res. 2002 Dec;11(4):289-95.

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Influence of pulsating magnetic field used in magnet therapy and magnet stimulation on cortisol secretion in human.

Woldanska-Okonska M, Czernicki J.

Oddzialu Rehabilitacji, Samodzielnego Publicznego Zakladu Opieki Zdrowotnej w Sieradzu.

The aim of our study was to test the influence of magnetic fields during magnetotherapy and magnetostimulation over a longer period of time (like in physiotherapy) on cortisol secretion in humans. The study population was divided into two groups: magnetotherapy group (16 men) and magnetostimulation group (10 men). Magnetotherapy in the form of magnetic field induction (2.9 microT; frequency--40 Hz; square wave; bipolar; Magnetronic MF--10 apparatus) was applied for 20 min to the lumbar area in patients with chronic low back pain. Magnetostimulation (Viofor JPS system; M2P2 program; induction--25-80 microT; frequency--200 Hz, complex saw-like shape with a plateau halfway the height of the wave; bipolar) was applied every day for 12 min in patients with the same health problem. In both groups, the procedures were repeated 15 times (about 10:00 a.m.) with weekend breaks. Serum samples were collected at 6:00, 12:00, 16:00 and 24:00 and estimated by the micromethod of chemiluminescence (DPC Poland; Cat. No. LKC01). The circadian profile of cortisol was determined prior to the application, a day and a month after application. The data were analyzed statistically, using paired and unpaired Student's test. Magnetotherapy affects the cortisol secretion in the circadian profile by decreasing its level at 16:00 a day after 15 applications, whereas magnetostimulation by increasing its level at 12:00 a month after 15 applications, which may suggest its long-term effect on hypothalamic-pituitary axis. The comparison of the results indicated that a day after magnetotherapy and magnetostimulation, the circadian curves of cortisol secretion differed significantly by about 100%. All hormone oscillations did not exceed the physiological norms of the circadian cortisol level, not reaching the level so high as in an intense stress. This suggests rather their controlling effect on the cortisol level than their significant stressogenic nature.

Med Pr. 2003;54(1):29-32.

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Effects of an acute D2-dopaminergic blockade on the somatosensory cortical responses in healthy humans: evidence from evoked magnetic fields.

Huttunen J, Kahkonen S, Kaakkola S, Ahveninen J, Pekkonen E.

BioMag Laboratory, Medical Engineering Centre Department of Clinical Neurophysiology, Helsinki University Central Hospital, P.O. Box 340, FIN-00029 HUS.

SUMMARY: We tested the possible role of dopaminergic activity in the processing of somatosensory afferent information in healthy humans. Somatosensory evoked magnetic fields (SEFs) were recorded in seven subjects in response to left median nerve stimulation. SEFs were obtained in all subjects after oral administration of 2 mg haloperidol, an antagonist to dopaminergic D2 receptors, and placebo, which were given in a randomized, double-blind cross-over design. SEFs were analyzed using a multiple equivalent current dipole (ECD) model, with one dipole at the right primary somatosensory cortex (SI) and at both left and right secondary somatosensory cortices (SII). The earliest responses from SI, peaking at about 20 ms (N20m) and 35 ms (P35m), were not affected by haloperidol. A later deflection peaking at about 75 ms (P60m), however, was slightly reduced (p < 0.05). Responses arising from SII were not significantly changed. The results suggest that dopaminergic activity may be involved in modulating somatosensory processing after the initial stages of cortical activation.

Neuroreport. 2003 Aug 26;14(12):1609-12.

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Effects of magnetic field exposure on open field behaviour and nociceptive responses in mice.

Del Seppia C, Mezzasalma L, Choleris E, Luschi P, Ghione S.

Institute of Clinical Physiology, CNR, via Moruzzi 1, 56124 Pisa, Italy.

Results of previous studies have shown that nociceptive sensitivity in male C57 mice is enhanced by exposure to a regular 37 Hz or an irregularly varying (<1 Hz) electromagnetic field. In order to test whether these fields affect more generally mouse behaviour, we placed Swiss CD-1 mice in a novel environment (open field test) and exposed them for 2 h to these two different magnetic field conditions. Hence, we analysed how duration and time course of various behavioural patterns (i.e. exploration, rear, edge chew, self-groom, sit, walk and sleep) and nociceptive sensitivity had been affected by such exposure. Nociceptive sensitivity was significantly greater in magnetically treated mice than in controls. The overall time spent in exploratory activities was significantly shorter in both magnetically treated groups (< 1 Hz, 33% and 37 Hz, 29% of total time), than in controls (42%). Conversely, the time spent in sleeping was markedly longer in the treated groups (both 27% of total time) than in controls (11%). These results suggest that exposure to altered magnetic fields induce a more rapid habituation to a novel environment.

Behav Brain Res. 2003 Sep 15;144(1-2):1-9.

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