As always,
@RonG and @Warrior664 have some great insight. As they noted, there's no downside to asking for an increased rating, though there might not be much of an upside either.
To piggyback off of what they said, there's one important note to consider. The "one-year-past-discharge" rule with VA ratings applies to your
effective date, not
service connection.
Your effective date is the date that the VA starts paying you for a condition. After you get off Active Duty, anything that you file for within a year gets back-dated to the day you left AD. Even if you wait 11.5 months to file, you still get a check for all of that time back to the day after your discharge. That's the benefit of filing within a year.
However, there is no rule that says that anything you ask for within that year will be granted. You will still need to prove service connection, meaning that your time on Active Duty caused or aggravated your sleep apnea. It's best to have a sleep study from Active Duty showing a diagnosis of sleep apnea - then you're a shoe in. But without that, you'll need something else to prove to the VA that your condition was incurred or aggravated while you were entitled to basic pay.
There are some conditions that you don't need to go through all those hoops for. They're listed in 38 CFR 3.309(a) (
https://www.law.cornell.edu/cfr/text/38/3.309). These conditions are automatically service-connected if they show up within a year of you leaving Active Duty, often because sound medical principles dictate that by the time you're showing symptoms, the disease is at least a year old. The list includes things like ALS and multiple sclerosis. However, you'll note that sleep apnea isn't on that list.
There are ways to strengthen a claim for service connection. The most common one is to get a letter from your doctor saying that, based on his review of your clinical history and your test results, he thinks it is more likely than not that the condition was incurred or aggravated during service.
Best of luck with your claim! I agree with the above commenters - it's worth it to try and get the extra 50% even if it's not going to add to your paycheck each month directly.
