We studied 50 consecutive patients to test the hypothesis that successful t
reatment of obstructive sleep apnea with nasal continuous positive airway p
ressure (nasal CPAP) will decrease automobile accidents in patients with sl
eep apnea. Thirty-six (72%) of the patients reported using nasal CPAP regul
arly during 2 yr. Fourteen patients reported they had not used CPAP during
2 yr. The patients with sleep apnea in this study had a higher automobile c
rash rate than all drivers in the state of Colorado (0.07 versus 0.01 crash
per driver per year, p < 0.02). Patients who were treated with nasal CPAP
had a lower crash rate while being treated than before treatment (0.07 vers
us 0 crash per driver per year, p < 0.03). Untreated patients with sleep ap
nea continued to have a high crash rate (0.07 crash per driver before and a
fter diagnosis). Drivers with sleep apnea were reluctant to report their au
tomobile crashes, for the drivers in this study reported only one-third of
the crashes in which they were involved. This is the first study to confirm
with traffic records that patients with sleep apnea have fewer automobile
crashes while being treated with nasal CPAP.