Coemergence of insomnia and a shift in the Th1/Th2 balance toward Th2 dominance.
OBJECTIVE
Insomnia is associated with physical and mental disorders. We examined the effect of insomnia on immune functions, focusing on the T helper 1 (Th1)/ T helper 2 (Th2) balance, by a cross-sectional design.


METHODS
We provided a self-administered questionnaire to evaluate sleep habits, smoking and medical disorders to 578 men without any toxic exposure (20-64 years old), and measured natural killer (NK) cell activity in 324 men and production of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) after stimulation with phytohemagglutinin in 254 men. According to the criteria of DSM-IV, in which insomnia is classified into primary and secondary insomnia, we assessed the effect of insomnia on immune functions, controlling for age and smoking in groups with and without medical disorders.


RESULTS
The prevalence of insomnia in the present study was 9.2%. In the absence of medical disorders, insomniac men had a significantly lower IFN-gamma and ratio of IFN-gamma to IL-4 than noninsomniac men. Men with insufficient sleep or difficulty initiating sleep (DIS) had a significantly lower IFN-gamma to IL-4 ratio than those not suffering from insufficient sleep or DIS. In the presence of medical disorders, insomniac men had significantly higher IL-4 than noninsomniac men. Men with difficulty maintaining sleep (DMS) had a significantly lower IFN-gamma to IL-4 ratio than men without DMS. NK cell activity was independent of insomnia.


CONCLUSIONS
The present results showed a link between insomnia unrelated to medical disorders and a shift in the Th1/Th2 balance toward Th2 dominance, indicating that the relationship between sleep quality and the etiology of immune-related diseases should be reconsidered.
Sakami
Shotaro
S
Division of Psychosomatic Research, National Institute of Mental Health, Chiba, Japan.
Ishikawa
Toshio
T
Kawakami
Norito
N
Haratani
Takashi
T
Fukui
Akira
A
Kobayashi
Fumio
F
Fujita
Osamu
O
Araki
Shunichi
S
Kawamura
Noriyuki
N
D000328:Adult; D003430:Cross-Sectional Studies; D015536:Down-Regulation / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000187:drug effects / Q000276:immunology; D015847:Interleukin-4 / Q000276:immunology; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology*; D016131:Lymphocyte Subsets / Q000187:drug effects / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D015213:Neuroimmunomodulation / Q000187:drug effects / Q000276:immunology*; D010835:Phytohemagglutinins / Q000494:pharmacology; D007319:Sleep Initiation and Maintenance Disorders / Q000276:immunology* / Q000503:physiopathology; D012907:Smoking / Q000276:immunology; D011795:Surveys and Questionnaires; D018417:Th1 Cells / Q000187:drug effects / Q000276:immunology*; D018418:Th2 Cells / Q000187:drug effects / Q000276:immunology*
D010835:Phytohemagglutinins; D015847:Interleukin-4; D007371:Interferon-gamma