Thirty-six female subjects (age 25-45 years) without sleep complaints (n=18) or with insomnia (n=18) will enroll in a interventional study measuring the reaction to and effects of either neutral or stressful events during driving. Through questionaires and intake polysomnography, clinical levels of depression and anxiety will be excluded as well as sleep medication use and alternative sleep disorders than insomnia. Stress levels will be measured through skin conductance and heart rate variability during events and through nighttime polysomnography (PSG). Effects on sleep architecture and arousal levels will be measured through nighttime PSG.