Like all biological processes, activity in the body's nervous system produces chemical waste products which need to be removed. It's been known for many years that the waste (proteins etc.) from the Central Nervous System (CNS) is removed and processed by the Lymphatic System and the CerebroSpinal Fluid. The question arises ; how does the main component of the CNS - the brain - get rid of its waste products?

It was only in 2012 that the major 'drainage system' for the brain - now called the Glymphatic System - was discovered. And in 2014, a network of fluid-carrying tubes called the meningeal lymphatic vessels, at the base of the outer brain membrane, were found to be a fundamental part of the system.

Recent work has shown that meningeal lymphatic vessels (mLVs), mainly in the dorsal part of the skull, are involved in the clearance of cerebrospinal fluid (CSF), but the precise route of CSF drainage is still unknown.

Source :Nature, volume 572, pages 62–66

Many questions remain regarding the modes of operation of the system. For example, it was initially thought that the system mainly operates at night, during sleepplugin-autotooltip__plain plugin-autotooltip_bigSleep

"The purposes and mechanisms of sleep are only partially clear and are the subject of intense research"

Source Wikipedia"

Although extensive research in humans and animals has shown unequivocally that sleep is essential, the reasons why it's required are as yet unknown. Long term sleep deprivation not only severely impairs cognitive and motor skills, it's now been shown that it can cause physical damage to brain structure - and, in extreme cases, irreversible damage.. But this has now been called into question.(ref.). In addition, there may be other as yet undiscovered pathways for drainage.

Many research groups are currently investigating the system. It's possible that faulty Glymphatic drainage may cause a build up of toxic substances in the brain, and possibly lead to (or exacerbate) Motor Neurone diseaseplugin-autotooltip__plain plugin-autotooltip_bigMotor Neurone disease

Motor Neurone disease, also known as Amyotrophic lateral sclerosis (ALS) and Lou Gehrig's disease, is a rare, progressive, neurological condition that involves degeneration of the nerve cells (neurons) responsible for controlling voluntary muscle movement., Alzheimer's diseaseplugin-autotooltip__plain plugin-autotooltip_bigAlzheimer's disease

"Alzheimer’s disease is a chronic progressive neuro-degenerative disorder characterised by three primary groups of symptoms. The first group (cognitive dysfunction) includes memory loss, language difficulties, and executive dysfunction (that is, loss of higher level planning and intellectual coordination skills). The second group comprises psychiatric symptoms and behavioural disturbances — for example, depression, hallucinations, delusions, agitation — collectively termed …, Parkinson's diseaseplugin-autotooltip__plain plugin-autotooltip_bigParkinson's disease

Also known as Parkinson disease, Parkinson's, idiopathic Parkinsonism, primary Parkinsonism, PD, or paralysis agitans - is a degenerative disorder of the central nervous system resulting from the death of dopamine-containing cells in the , Huntington's diseaseplugin-autotooltip__plain plugin-autotooltip_bigHuntington's disease

Huntington disease is an inherited, progressive, incurable neurodegenerative disorder that primarily affects cells in the brain.

The genetic components which trigger Huntington's disease were discovered in the 1990's. Sufferers have a mutation in the and similar problems.