Difficulty breathing through nose at night the cause of sleep apnea?

Usually not. Nasal obstruction can worsen sleep apnea but in most cases it is not the cause. Sometimes nasal obstruction is not really nasal, but due to throat obstruction, too. Nasal obstruction should be treated as even in absence of sleep apnea it affects sleep quality and daytime function. For some patients, treatment of nasal obstruction can aid in the treatment of sleep apnea.
No. If the nose is the only problem, you will simply breathe thru the mouth. The critical blockages occur in the back of the mouth and down the throat.

Related Questions

Can sleep apnea cause difficulty breathing throughout the day?

No. Sleep apnea is a disordered breathing during sleep. Most of those with sleep apnea are overweight and due to the pressure of the chest can have difficulty breathing anytime but not because of the sleep apnea. The are others like pickwickian syndrome or hypoventilation syndrome which can be present when awake. Also be aware of other conditions such as the heart or copd.

I have difficulty breathing when lying down. How do I tell if this is "Obstructive sleep apnea" or "Heart failure"? I do have Obstructive Sleep Apnea

Orthopnea. The symptom is called orthopnea. The way to find out if it's heart failure is to go to a doctor and find out if it's heart failure. The doctor may be able to tell you right there and then or (s)he may have to run some tests.

How do I know of I have sleep apnea our upper airway resistance syndrome? What came first? Cause of breathing difficulty? Tight neck muscles quickly

Sleep study. You should first be evaluated by a physician who can examine you and make sure there are no other obvious causes of breathing difficulty. The best way to evaluate sleep apnea vs upper airway resistance syndrome is with an overnight sleep study. You may be monitored in a sleep lab or sometimes at home with many sensors to help make a diagnosis.
Get checked. It is very easy to establish, sleep study will tell you whether you have central or obstructive sleep apnea or even uars.

Could having sleep apnea for so many years be the cause in having breathing problems when I exercise?

Potentially. Sleep apnea causes cardiovascular problems and pulmonary hypertension. But also, many other factors like nasal valve and septum issues, narrow posterior airway, cardiomyopathy, valvular problems, and many more be the cause as well.
Not directly. Sleep apnea is a co-factor or variable in many things (some say all disease), including cardiovascular issues. This would be more of an indirect contributor to your condition, but there are likely other factors involved as well.

I have difficulty breathing through nose when sleeping with head turned to left. There's almost no air flow. Breathing is normal when I turn to right.

Nasal obstuction. Could have many causes like sinus conditions or allergy which are transient or polyps, or a deviated septum possibly on the right side. Lying on one side causes an increase in blood flow due to gravity so you end up with both sides blocked.

For 2 years I have difficulty breathing. I have shortness of breath & can't breath through my nose unless im sleeping. Have to bend over & breath deep.

Sob. Your shortnessof breath may be due to a nasal polyp or deviated septum. Consult an entspecialist for evaluation anf d treatment.
Need ENT/ allergy. And pulmonary consults. If everything has been tested and has come back normal but I would recommend that you get a referral to a tertiary care university center for a more high-level evaluation. I can't tell if your ocd perhaps even plays a role in this. You should have your psychiatrist on board with these consultations. Hopefully with everyone putting their minds together they will be able to come up with a solution to your problem. Best wishes.

Why am I being studied for sleep apnea when I have no trouble breathing?

Sleeping apnea. You may be breathing just fine when you are awake, but when you go into deep sleep you may not be breathing deeply enough to keep your oxygen to adequate levels.

Are sleep apnea, trouble breathing awake and asleep and GERD part of pure autonomic falure or multiple system atrophy? Thanks.

The diseases. You are referring to are rare whereas the other items not necessarily. Talk to your physician & get answers.
Yes and No. Sleep apnea, troubled breathing and gerd might be symptoms involved with multiple system atrophy but not typically involved with pure autonomic failure.