Spontaneous sigh rates during sedentary activity: watching television vs reading.
BACKGROUND
Spontaneous sighs are thought to play an important role in preventing atelectasis and in regulating airway tone. Recent studies have provided a mechanism by which expansion of the lungs could cause relaxation of smooth muscle.


OBJECTIVE
To investigate breathing patterns during 2 forms of sedentary behavior: reading and watching television.


METHODS
Breathing patterns were monitored for 1 to 2 hours to document respiratory rates and sigh rates. Each participant was monitored while reading and while watching a movie on videotape. During the first experiment (17 controls), metabolic rates were also measured. In the second experiment (18 controls and 9 patients with mild-to-moderate asthma), only breathing patterns were monitored.


RESULTS
There were no significant differences in respiratory or metabolic rates between the 2 activities. In contrast, in the first experiment, 13 of 17 controls had lower sigh rates while watching a videotape than while reading (P < .01). In the second experiment, the sigh rate was significantly lower overall while watching a videotape (mean, 13.7 sighs per hour; range, 1.8-26.0 sighs per hour) than while reading (mean, 19.3 sighs per hour; range, 7.7-30.0 sighs per hour) (P < .001). A similar decrease was observed in patients with asthma (P < .01).


CONCLUSIONS
Given that many children and adults watch television for 5 or more hours per day, breathing patterns during this time may be relevant to lung function. Our results demonstrate that prolonged periods of watching a videotape are associated with lower sigh rates than while reading. Further research is needed to determine whether these changes are relevant to increased bronchial reactivity.
Hark
William T
WT
Asthma and Allergic Diseases Center, University of Virginia, Charlottesville, Virginia 22908, USA.
Thompson
William M
WM
McLaughlin
Timothy E
TE
Wheatley
Lisa M
LM
Platts-Mills
Thomas A E
TA
D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D011932:Reading; D012143:Respiratory Physiological Phenomena; D013690:Television