**Abstract**

This chapter focuses in the interrelationship between sleep and two neurodegenerative disorders: Amyotrophic Lateral Sclerosis [ALS] and Parkinson's disease [PD]. Sleep disorders have deleterious effect on the quality of life and survival in these neurodegenerative disorders, while the reverse is also true where neurodegenerative disorders significantly impair the sleep, leading to a vast sleep complains that worsen the clinical course of these conditions. Other neurodegenerative disorders such as dementias, spinocerebellar ataxias, atypical parkinsonism, etc. will not be cover in this chapter.

**Keywords:** sleep, amyotrophic lateral sclerosis, hypoventilation, Parkinson's disease, parkinsonism
