If he truly does have a confirmed “lack of oxygen” at night, the cause of his low oxygen levels needs to be determined with certainty and treated. It may turn out that he would benefit from the use of supplemental oxygen with sleep, but that should not be assumed.
That he “falls asleep constantly” suggests a sleep disturbance, such as what is called Sleep
ApneaApnea monitor
Apnea of prematurity
Breathing - slowed or stopped
Central sleep apnea
Obstructive sleep apnea
Sleep apnea. The most
commonCommon cold type of this
disorderAdjustment disorder
Anorexia nervosa
Asperger syndrome
Autism
Autoimmune disorders
Bipolar disorder
Bipolar disorder
Bleeding disorders
Borderline personality disorder
Bulimia
Chronic motor tic disorder is what is called
obstructiveAcute bilateral obstructive uropathy
Obstructive uropathy sleep apnea and this is characterized by heavy snoring and by the actual cessation of breathing, sometimes for 30-60 seconds or more. This is a treatable condition.
Other possibilities to be considered, and not necessarily the cause, would include: CHF that is actually more than “mild”, depression, gastroesophageal reflux (as a cause of cough). Between them, the cardiologist and pulmonary specialist should be able to diagnose the cause of your father’s respiratory symptoms and sleepiness. If they cannot, you should request a 2nd opinion from another lung specialist.
A lack of sleep could be responsible for many of his symptoms (sleepiness and lethargy) but you should ask his primary care physician to consider other possibilities for those particular symptoms, such as a hormonal deficiency.
Your father is clearly not capable of fending for himself, so you must be his advocate. Do not hesitate to ask questions of his doctors.
Good luck