Non-invasive ventilation or BiPAP®, which is a form of breathing support delivered through a facemask, is a successful treatment for the respiratory complications of amyotrophic lateral sclerosis (ALS). It has been shown to prolong survival, improve quality of life, and improve cognitive function. It is widely used among patients with ALS who have advanced breathing difficulties. It is not known whether there is benefit to using non-invasive ventilation earlier in the disease course.