Sleep disturbances are common in pregnancy, and the incidence increases during the third trimester. Light and specially the blue wavelengths of light, is affecting sleep and the circadian rhythm. The main aim of this randomized controlled study is to investigate the effect of Blue-blocking glasses (BB-glasses) used in the evening and night on sleep and mood in pregnant women in the third trimester. The outcome measures assess sleep variables, alertness, melatonin level, sleepiness (subjectively), mood and symptoms of anxiety and depression. In addition we want to measure the pregnancy related sleep problems, alcohol intake, physical activity and perceives stress in the study population, and the association with daily/nightly light exposure.