The Central Nervous System—consisting of the brain and spinal cord—is flushed by the cerebrospinal fluid. The fluid corresponds to the intercellular fluid. The outflow from the brain parenchyma mainly occurs via the perivascular Virchow-Robin spaces into the outer cerebrospinal fluid space. True lymphatic vessels are only found in or on the dura mater, the hard brain membrane. The importance of lymphatic drainage for the function of the CNS seems undisputed, even though in humans the venous outflow of cerebrospinal fluid via the arachnoid granulations seems to have a higher value compared to animals. The cervical lymph nodes bear the main burden of the cranial cerebrospinal fluid and the lumbosacral ones that of the spinal cerebrospinal fluid. Sleep plays a special role, as the most effective drainage of the CNS takes place during sleep. A connection with amyloid deposits and neurodegenerative diseases is becoming increasingly clear. The simple tools (lots of fluid, lots of sleep) still seem to be the most practical.