Esophageal pressure (Pes) monitoring can be performed during polysomnography with a thin, water-filled catheter connected to a transducer. The resulting quantitative assessment of respiratory effort aids in the diagnosis of sleep-related breathing disorders, but little is known about the potential effect of the procedure on sleep architecture. We monitored Pes during polysomnography in 155 patients and compared their sleep architecture with that of 155 matched patients who slept without esophageal catheters. Cases were matched for age, sex, and severity of respiratory disturbance during sleep. Esophageal manometry was associated with small but statistically significant (p < 0.05) decrements in total recording time, total sleep time, sleep efficiency, percent Stage 2 sleep, and percent rapid-eye-movement (REM) sleep, and with increases in latency to REM sleep, latency to persistent sleep, and percent Stage 3/4 sleep. The differences were of such small magnitude that their clinical significance is doubtful. The number of awakenings per hour of sleep, latency to sleep onset, and percent Stage 1 sleep were no different when esophageal manometry was used. We conclude that the effects of monitoring Pes on sleep architecture are minimal, and that the decision of whether or not to use the technique can be based to a large extent on whether quantitative information about respiratory effort will be useful.