Sleep as a mediator of the stress-immune relationship.
OBJECTIVE
To evaluate the role of sleep in the relationship of intrusive thoughts/avoidance behaviors to natural killer cell (NKC) number and function.


METHODS
Twenty-nine individuals seeking treatment for bereavement-related depression were studied in the sleep laboratory. Background and clinical variables, including the Impact of Event Scale (IES) and the Hamilton Rating Scale for Depression (HRSD), were administered during the week preceding a 3-night sleep study. Blood samples were collected upon awakening after the second or third night of sleep.


RESULTS
Greater frequency of intrusive thoughts and avoidance behaviors was associated with more time spent awake during the first non-rapid eye movement period (NREM-1) and lower NKC number (p values < .01). Greater time spent awake during NREM-1 was associated with lower NKC numbers (p < .05). Regression analyses revealed that the significant relationship between symptoms of intrusion/avoidance and NKC number was no longer significant when time spent awake during NREM-1 was entered into the regression equation. Time spent awake during NREM-1 accounted for 12% of the variance in NKC number (p < .05), whereas intrusion/avoidance accounted for 7% of the variance in NKC number (NS).


CONCLUSIONS
These results suggest that EEG-assessed sleep may be a significant correlate of the stress-immune relationship.
Hall
M
M
Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pennsylvania 15213, USA.
Baum
A
A
Buysse
D J
DJ
Prigerson
H G
HG
Kupfer
D J
DJ
Reynolds
C F
CF
D000328:Adult; D000368:Aged; D001601:Bereavement; D003674:Defense Mechanisms; D003865:Major Depressive Disorder / Q000276:immunology / Q000523:psychology / Q000628:therapy; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D010555:Personality Inventory; D017286:Polysomnography; D011598:Psychoneuroimmunology; D012894:Sleep Stages / Q000276:immunology*; D012895:Sleep, REM / Q000276:immunology; D013315:Stress, Psychological / Q000150:complications* / Q000276:immunology