The increasing use of 24 h ambulatory blood pressure monitoring provides important information on daytime and on nighttime pressures. Today, there is no clear recommendation on how to manage an increase in nighttime blood pressure. The goal of this article is to review the normal values of nighttime blood pressure and to discuss the most recent scientific data linking nocturnal blood pressure with an increased cardiovascular risk. We have now a good evidence that elevated nocturnal pressures are associated with an increased risk of developing cardiac, renal and cerebral complications. However, no clinical study has demonstrated the interest of treating specifically nighttime blood pressure. Nonetheless, in high risk patients, it may be wise to consider a treatment that lowers blood pressure as effectively during the day and during the night.