Citation Nr: 21029027 Decision Date: 05/12/21 Archive Date: 05/12/21 DOCKET NO. 15-00 037A DATE: May 12, 2021 ORDER Entitlement to service connection for a sleep disability, to include sleep apnea, and to include as secondary to the Veteran's service-connected disabilities, is denied. FINDING OF FACT The preponderance of the evidence is against finding that the Veteran has a sleep disability, to include sleep apnea, that is not a symptom of his service-connected psychiatric disorder and/or that is related to service or secondary to a service-connected disability. CONCLUSION OF LAW The criteria for entitlement to service connection for a sleep disability, to include sleep apnea, have not been met. 38 U.S.C. §§ 1101, 1112, 5103A, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.307, 3.309, 3.310, 3.317. REASONS AND BASES FOR FINDING AND CONCLUSION The Veteran served on active duty in the United States Army from July 1975 to July 1995, to include service in Southwest Asia. This matter comes before the Board of Veterans' Appeals (Board) on appeal from a March 2010 rating decision issued by a Department of Veterans Affairs (VA) Regional Office (RO). In May 2018, the Veteran testified at a Board hearing before the undersigned Veterans Law Judge. A copy of the hearing transcript is associated with the claims file. In July 2018, August 2019, and November 2020, the Board remanded the matter to the RO for further development. Entitlement to service connection for a sleep disability, to include sleep apnea The Veteran contends that he has a sleep disorder, to include sleep apnea, that is related to service. Specifically, he argues that he had a sleep disorder during service, which manifested into sleep apnea. For the reasons set forth below, the Board concludes that service connection for this issue must be denied. Service connection may be granted for a disability resulting from a disease or injury incurred in or aggravated by active service. 38 U.S.C. §§ 1110, 1131; 38 C.F.R. § 3.303(a). Service connection may also be granted for any disease diagnosed after discharge from service, when all the evidence, including that pertinent to service, establishes that the disease was incurrent in service. 38 C.F.R. § 3.303(d). Generally, to prove service connection, there must be competent, credible evidence of (1) a current disability, (2) an in-service incurrence or aggravation of a disease or injury, and (3) a nexus, or link, between the current disability and the in-service disease or injury. See, e.g., Davidson v. Shinseki, 581 F.3d 1313 (Fed. Cir. 2009). Service connection may be established on a secondary basis for a disability which is proximately due to or the result of a service-connected disease or injury. 38 C.F.R. § 3.310(a). Establishing service connection on a secondary basis requires evidence sufficient to show (1) that a current disability exists and (2) that the current disability was either (a) proximately caused by or (b) proximately aggravated by a service-connected disability. 38 C.F.R. § 3.310(a), (b). Additionally, while the United States Court of Appeals for Veterans Claims (Court) held in Marcelino v. Shulkin, 29 Vet. App. 155, 158 (2018) that "there is currently no provision in the rating schedule to compensate for obesity," VA's Office of General Counsel (OGC) issued an opinion that a claim for secondary service connection may be based on obesity as an "intermediate step" between a service-connected disability and a current disability that may be service connected on a secondary basis under 38 C.F.R. § 3.310(a). VAOPGCPREC 1-2017. This "intermediate step" under 38 C.F.R. § 3.310(a) equates to an inquiry into proximate cause requiring a three-step analysis, namely of (1) whether the service-connected disability caused the Veteran to become obese; (2) if so, whether the obesity as a result of the service-connected disability was a substantial factor in causing the current disability; and (3) whether the current disability would not have occurred but for obesity caused by the service-connected disability. If these questions are answered in the affirmative, the Veteran's sleep apnea may be service connected on a secondary basis. A determination of proximate cause is one of fact for determination by adjudication personnel. In the absence of proof of a current disability, there can be no valid claim for service connection. Brammer v. Derwinski, 3 Vet. App. 223 (1992). Service connection may only be awarded to an applicant who has a disability existing on the date of application or at any time during the appellate period, not for a past disability. Degmetich v. Brown, 8 Vet. App. 208 (1995); 104 F.3d 1328, 1332 (1997)); Romanowsky v. Shinseki, 26 Vet. App. 289, 294 (2013). Further, Persian Gulf veterans may be entitled to service connection for a chronic disability resulting from an undiagnosed illness or medically unexplained chronic multi-symptom illness in certain circumstances. 38 U.S.C. § 1117; 38 C.F.R. § 3.317. A Persian Gulf veteran is defined as one who served on active military, naval, or air service in the Southwest Asia Theater of Operations during the Persian Gulf War. 38 C.F.R. § 3.317(e)(1). The Persian Gulf War began on August 2, 1990. 38 C.F.R. § 3.2(i). The Southwest Asia Theater of Operations refers to Iraq, Kuwait, Saudi Arabia, the neutral zone between Iraq and Saudi Arabia, Bahrain, Qatar, the United Arab Emirates, Oman, the Gulf of Aden, the Gulf of Oman, the Persian Gulf, the Arabian Sea, and the Red Sea. 38 C.F.R. § 3.317(e)(2). As the evidence shows that Veteran served on active duty in the Southwest Asia Theater of Operations during the Persian Gulf War, he is considered a Persian Gulf Veteran under the applicable regulations. Service connection may be warranted for a Persian Gulf Veteran who exhibits objective indications of a qualifying chronic disability that became manifest during active military, naval, or air service in the Southwest Asia Theater of Operations during the Persian Gulf War, or to a degree of 10 percent or more not later than not later than December 31, 2021. 38 C.F.R. § 3.317(a)(1). For purposes of 38 C.F.R. § 3.317, there are three types of qualifying chronic disabilities: (1) an undiagnosed illness; (2) a medically unexplained chronic multi symptom illness; and (3) a diagnosed illness that the Secretary determines in regulations prescribed under 38 U.S.C. § 1117 (d) warrants a presumption of service-connection. Under the applicable provisions, an undiagnosed illness is defined as a condition that by history, physical examination, and laboratory tests cannot be attributed to a known clinical diagnosis. A medically unexplained chronic multi symptom illness is one defined by a cluster of signs or symptoms, and specifically includes chronic fatigue syndrome, fibromyalgia, and irritable bowel syndrome, and any other illness that the Secretary determines meets the criteria in paragraph (a)(2)(ii) of this section for a medically unexplained chronic multi symptom illness. A "medically unexplained chronic multi symptom illness" means a diagnosed illness without conclusive pathophysiology or etiology, which is characterized by overlapping symptoms and signs and has features such as fatigue, pain, disability out of proportion to physical findings, and inconsistent demonstration of laboratory abnormalities. Chronic multi-symptom illnesses of partially understood etiology and pathophysiology will not be considered medically unexplained. 38 C.F.R. § 3.317(a)(2)(ii). When there is an approximate balance of positive and negative evidence regarding any issue material to the determination of a matter, the Secretary shall give the benefit of the doubt to the claimant. 38 U.S.C. § 5107; 38 C.F.R. § 3.102; see also Gilbert v. Derwinski, 1 Vet. App. 49, 53 (1990). Turning to the evidence of record, the Veteran's active duty service treatment records (STRs) are silent as to any treatment or diagnosis of sleep apnea. His STRs, however, are rife with complaints of sleep disturbances and include diagnoses of sleep paralysis and insomnia. In this regard, an August 1978 STR notes the Veteran complained of difficulty sleeping, an October 1978 STR notes the Veteran had sleep disturbance, and a November 1978 STR notes anxiety with related complaints including sleep disturbance. Thereafter, a February 1979 STR reflects that the Veteran had insomnia. Moreover, a 1983 Fort Knox electroencephalogram (EEG) report notes that the Veteran had a history of sleep paralysis. STRs in 1983 and 1984 also reflect complaints related to sleep paralysis while an April 1984 STR indicates the Veteran had sleep paralysis and was taking medication for it. Likewise, a June 1984 STR reflects that the Veteran experienced episodes of sleep paralysis for years and that he may benefit from evaluation at a sleep center if the condition persists. His October 1984 periodic Report of Medical Examination further reflects that the Veteran had treatment for an inability to move his extremities after lying down and had occasional episodes approximately once a month. Thereafter, a March 1988 medical officer screening note reflects that the Veteran's current problems include a sleep disorder while a September 1991 periodic Report of Medical Examination also reflects that the Veteran had occasional sleep problems. Additionally, an October 1994 STR shows that the Veteran had trouble sleeping and felt twitching throughout his body while a December 1994 STR indicates sleep problems from twitching. The Veteran's April 1995 retirement Report of Medical Examination is silent for a diagnosis or notation of sleep apnea; however, his April 1995 separation Report of Medical History reflects that the Veteran reported having frequent trouble sleeping and that he sometimes had to take sleeping pills. The Board notes that the Veteran has reported that he underwent a sleep study in service, was diagnosed with sleep apnea in service, and received a continuous positive airway pressure (CPAP) machine in or approximate to his discharge from service. See May 2018 Board hearing transcript, pp. 5-11; March 2019 VA examination. However, while there are many medical records from this time period, there is no evidence of a sleep study performed in service or approximate to his discharge from service nor is there any indication a sleep study was ordered, or any evidence of a diagnosis of sleep apnea during this time period. Indeed, while an October 1995 VA general medical examination reflects the Veteran's complaints that he seemed to sleep more during the day and consequently did not want to sleep at night, the examination itself is silent regarding any treatment or diagnosis of sleep apnea. Following his discharge from service, the post service medical records reflect that the Veteran was continuously treated for insomnia. See e.g., November 2000 treatment record (noting the Veteran still has trouble sleeping in the night without medication); July 2002 treatment record (reflecting depression/insomnia); May 2004 treatment record (noting a history of insomnia); and July 2015 VA treatment record. In correspondence received by VA in May 2006, the Veteran's brother indicated that the Veteran's medications for his psychiatric problems affected his sleep. The records also denote sleep complaints and disturbances. See July 1999 treatment record (noting the Veteran is fatigued and his sleep is disrupted every night); September 2000 treatment record (reflecting the Veteran is sleeping too much and was assessed with major depressive disorder); October 2000 private treatment record (reflecting complaints of muscle spasm and muscles stiffness usually at night while sleeping and that he wakes up with it); April 2005 Veteran Readiness and Employment Case Note (reflecting the Veteran's report that he has a sleep problem that requires medications to sleep); November 2007 treatment record (reflecting depression accompanied by sleeping less); January 2008 treatment record (reflecting difficulty falling asleep and middle of the night awakening); January 2008 treatment record (reflecting that psychological symptoms included sleep disturbances); and June 2009 VA treatment record (reflecting a history of poor sleep). Upon careful review of the record, the Board finds that the first notations of sleep apnea in the medical records appear in September 2009. In this regard, a September 2009 treatment record reflects that the Veteran reported he was working nights as security and was having a terrible time with insomnia and anxiety. The record further reflects that the Veteran "feels like his sleep apnea has reactivated" and that his spouse says he snores loudly and awakens multiple times in the morning when he sleeps and that he has somnolence. The treating physician noted that the Veteran needed a sleep apnea work up again and that the Veteran also saw a physician for anxiety and insomnia. Thereafter, an October 2009 treatment record reflects the Veteran reported that he had daytime somnolence and he was assessed with OSA. A November 2009 treatment record also reflects that the Veteran had known sleep apnea, had brought part one of his sleep study report with him, needed CPAP titration, and was assessed with OSA. Although the medical records do not contain the actual 2009 sleep study report, the contemporaneous medical evidence, including the above November 2009 treatment record, corroborates that the Veteran underwent a sleep study approximate to this time. See e.g., June 2011 treatment record (reflecting the Veteran's reports of a sleep study in 2009); November 2011 treatment record (noting the Veteran underwent a sleep study one to two years ago). The subsequent treatment records further reflect that the Veteran continued to complain of sleep impairments. See March 2012 treatment record (reflecting sleep disturbances and decreased functional ability); September 2014 VA treatment record (reflecting that the Veteran slept four to five hours a night, is sleepy during the day, and naps a lot); July 2015 VA treatment record (reflecting the Veteran's reports that he cannot sleep without medication and uses a CPAP machine); April 2016 VA treatment record (reflecting the Veteran's reports that he sometimes goes four days without sleeping); and February 2017 VA treatment record (reporting that he sleeps two to eight hours a night). The Veteran was also afforded a VA mental disorders examination in September 2014 where he was diagnosed with psychiatric disorders, to include major depressive disorder. Chronic sleep impairment was identified as one of the Veteran's symptoms of his diagnosed psychiatric conditions. The Veteran also underwent a sleep study in September 2014 and March 2019. The September 2014 sleep study report notes that clinically significant sleep disordered breathing was not identified and that this finding was inconsistent with the high pre-test probability of the Veteran having severe OSA. The March 2019 sleep study report is associated with the record and on an associated questionnaire, the Veteran reported that he has had this problem for 30 plus years. See March 2019 Sleep/Medical Questionnaire. However, a March 2019 VA pulmonary sleep/critical care note reflects that the Veteran's March 2019 sleep study was a negative overnight sleep study. In support of his claim, the Veteran provided testimony at the May 2018 Board hearing that he underwent a sleep study around 1984 and was subsequently given medication for a period of time. See May 2018 Board hearing transcript p.10-12. He also testified that he received a CPAP machine in 1995 or 1996 and that in service, or approximate to his discharge from service, he would stop breathing in his sleep and would wake up. Id. at pp. 5-7, 14. He also described that his spouse would wake him up because she would be tired of him moaning and groaning all night, which would also wake her up and explained that two weeks ago, he stopped breathing and felt like he could not move. Id. at pp. 7, 12. The Board notes that the Veteran has been afforded several VA opinions, to address his service connection claim, in September 2014, January 2015, March 2019, November 2019, and March 2021. The September 2014 VA examiner opined that the Veteran did not have a sleep disability, to include sleep apnea. As the evidence of record reflects that the Veteran has a sleep disability, to include sleep apnea, the Board does not assign any probative value to this opinion. Likewise, the August 2019 Board decision found that the January 2015 and March 2019 negative nexus opinions were inadequate to decide the claim because the VA examiners failed to reflect consideration of the post-service treatment records indicating the Veteran had sleep apnea and used a CPAP machine and did not take into account the Veteran's reports of symptoms and history. As such, the Board assigns no probative weight to these opinions. The Board notes, however, that the March 2019 VA examination reflects that the Veteran reported he received a diagnosis of sleep apnea in the 1980s during service and that he had a CPAP machine during and after service. The November 2020 Board decision also found that the November 2019 VA negative nexus opinion was inadequate, among other reasons, because the VA examiner did not address the evidence showing medical problems of daytime somnolence, an organic sleep disorder, and secondary insomnia. As such, the Board will also assign no probative weight to this opinion. A VA opinion regarding the Veteran's claim was last obtained in March 2021. The VA examiner first identified that the Veteran's known sleep disorders throughout the appeal period (i.e., from November 2009) were insomnia and obstructive sleep apnea (OSA). The examiner explained that the Veteran's insomnia was a manifestation of the Veteran's long-standing mental health disorders of anxiety and depression and did not constitute a distinct and separate disorder. In this vein, the VA examiner explained that while secondary insomnia was noted in some of the Veteran's post-military problem lists, this is another way to refer to insomnia due to a primary disorder (in this case depression with anxiety) and still does not constitute a separate disorder. The VA examiner further explained that the Veteran's OSA was established in the record as of November 2009 and that his March 2019 follow-up sleep study confirmed that he continued to have active sleep apnea. The examiner also explained that although the Veteran had diagnosed sleep paralysis in service, this condition is not chronic or recurrent based on the record nor is an ongoing condition after service or during the pendency of the appeal based on the record. The March 2021 VA examiner then found that it was less likely than not that the Veteran's claimed condition was related to his service. In this regard, the examiner explained that although the Veteran's insomnia has recurred often during and since his time in service, his insomnia is a symptom of his already service-connected major depressive disorder and does not represent a separate and distinct disorder that can be related back to his time in service. With respect to the Veteran's diagnosed OSA, the VA examiner found that such was not due to or incurred during service. She noted that while in September 2009, the Veteran reported to his primary care provider that his sleep apnea had reactivated, there is no record in the claims file for any diagnosis of or complaints of sleep apnea until September 2009. Similarly, the VA examiner acknowledged that although the Veteran later, during the pendency of his appeal, indicated that he received sleep studies in service, there is no documentation of such in the STRs nor any records suggesting sleep apnea or recommending/ordering sleep studies. Specifically, she reiterated that the record does not support the Veteran's report of receiving a sleep apnea diagnosis is the 1980s and having a CPAP machine during and after service, as well as in 1995/1996, because the record shows the Veteran never once reported a sleep apnea diagnosis to a medical provider after service, until 2009 when he requested a new sleep study. She also explained that the Veteran never reported to, and/or discussed with, any medical providers for years after service, or at the time of his separation examination from service, a diagnosis of sleep apnea. The examiner also noted that the Veteran's primary care provider, in a November 2009 treatment record, referenced a 2009 sleep study and that while the primary care provider indicated the Veteran's sleep apnea was "known" as of November 2009, this reference does not clarify when his sleep apnea was "known," if prior to 2009, and more likely represented the provider reiterating what the Veteran had subjectively reported. The VA examiner also found that although the Veteran had sleep paralysis in service, there is no further evidence that the Veteran had this disorder after his time in service and explained that this is a completely separate and unrelated disorder to sleep apnea because sleep paralysis is a parasomnia, which is a sleep disorder of behavior, in which features of rapid eye movement (REM) sleep intrude upon wakefulness in that the atonia of REM develops when the subject is awake or at least still aware and unable to move. On the other hand, sleep apnea is a sleep disorder specifically of breathing and, thus, is unrelated to and not caused by or causative for sleep paralysis. The VA examiner further explained the mechanisms of OSA and that the disability can only be diagnosed with a sleep study. In this regard, she explained that there are no sleep disturbance symptoms or subjectively observed sleep patterns that definitively identify the presence of a clinical sleep apnea disorder and that while snoring, difficulty staying asleep, and even witnessed apneas can be complaints in those with OSA, such complaints do not meet the criteria for a diagnosis of OSA. In the present case, the Veteran's diagnosis of OSA was not established in the record until 2009, which was 10 plus years after his separation from service. The examiner further acknowledged that while the Veteran was competent to report on observed symptoms, including difficulty sleeping or snoring, these symptoms, as she had discussed above, do not establish a diagnosis of sleep apnea and were not indicative of OSA in this case. In support of her conclusions, the VA examiner also cited to medical literature on OSA. As the VA examiner documented consideration of several treatment records noting sleep complaints, to include the September 2009 treatment record where the Veteran reported that he feels like his sleep apnea had reactivated and that he had somnolence, addressed the Veteran's lay statements, and documented review of the sleep studies and examinations of record, the Board finds that the examiner sufficiently addressed the evidence showing medical problems of daytime somnolence, sleep apnea, an organic sleep disorder, insomnia, and secondary insomnia. The March 2021 VA examiner also concluded, with detailed and separate rationale, that is less likely than not that the Veteran's claimed condition, to include insomnia and OSA, was caused by or aggravated by any of his service-connected disabilities, to include any medication or treatment for such. With respect to the Veteran's OSA, the VA examiner noted that while there is an increased prevalence of sleep apnea in those who are also diagnosed with major depression, the medical literature does not establish a causal relationship between the two because there are no evidence-based studies to support that major depression causes sleep apnea to develop. The examiner found the same to be true for GERD and noted that the Veteran's other service-connected disorders have no relationship, neuroanatomic or pathophysiologic, to sleep architecture or to the function of the upper airway and, thus, have no effects on the development or course of sleep apnea. The VA examiner further explained that while some medications have been shown to exacerbate OSA, no medications have been shown to cause the development of OSA, while in the Veteran's specific case, it is unlikely that he would have manifested sleep apnea related to his medications. In reaching this conclusion, the VA examiner detailed the Veteran's medications, onset of OSA, and included a citation to medical literature. The VA examiner further explained that although the original severity of the Veteran's OSA could not be determined, the evidence did not show that the Veteran's OSA progressed beyond its normal course due to any cause, including any service-connected disorders or treatments for the same. The examiner explained, based on the available sleep studies of records and treatment records showing inconsistent CPAP use, that the Veteran's OSA appears to have progressed as expected from mild to barely moderate over 10 years, which is a typical rate of deterioration for chronic OSA. The examiner explained there was no confirmed temporary or permanent exacerbation for any reason. The VA examiner also provided detailed rationale for why the Veteran's insomnia was not caused or aggravated by any service-connected disability, including that the Veteran's insomnia has waxed and waned in severity over time in relation to his depression and anxiety control, that the record does not otherwise show any clear progression of his insomnia over time, just expected fluctuations, and that the only chronic treatments the Veteran had over years were intended to, and did to varying degrees, help long term with his psychiatric disorder, and insomnia, rather than exacerbate or aggravate it. Finally, the March 2021 VA examiner found that the Veteran's sleep disability was less likely than not related to a specific exposure event during service in Southwest Asia and found it was less likely than not that the Veteran's service-connected disabilities, including medications, caused or aggravated the Veteran's obesity/being overweight or that the obesity/weight-gain caused or aggravated any or all of the Veteran's sleep disabilities. In this regard, the VA examiner found that the Veteran's sleep disability is a diagnosable chronic multi-symptom illness with a partially explained etiology. The VA examiner cited to medical literature and noted that while the exact cause for the upper airway collapse in OSA is not well understood, there are known risk factors for the development of OSA and environmental exposures play no known part in the development or progression of OSA. In this case, because the Veteran did not develop OSA until years after his time in service in Southwest Asia, and as no known environmental exposures, including those possible in Southwest Asia service, have a known relationship to OSA, it cannot be established that the Veteran's OSA developed during or due to Southwest Asia service. With respect to obesity, the VA examiner explained that obesity is a multifactorial condition that generally cannot be determined to be due to any specific set of conditions and that while the Veteran's weight has gradually gone up over time since service, this is not unexpected as the Veteran has aged. The examiner also detailed the Veteran's periods of weight loss since service and surges in weight gain, but noted there was no associated specific medications or progression of the Veteran's service-connected disabilities at the time of weight gain to relate such to that weight gain. The VA examiner additionally noted that although there is a well-established relationship between obesity and sleep apnea, in this case, the Veteran had lost ten pounds in the year before his OSA diagnosis and had an almost normal body mass index (BMI) at that time. The VA examiner further explained that when the Veteran's weight was at its highest point, in 2014, his OSA was essentially non-existent or so well controlled with treatment as to be non-diagnoseable on a sleep study that year. Thereafter, the March 2019 sleep study identified his OSA as moderate even though his weight actually went down relative to 2014. In light of this evidence, the VA examiner concluded that the Veteran's OSA specifically did not develop in a setting of obesity or even rising weight gain and is not correlated with rises in weight or BMI. In light of the above evidence, the Board finds that the preponderance of the evidence is against finding that the Veteran has a sleep disability, to include sleep apnea, that is related to his active duty service. First, the Board finds that the Veteran has a diagnosis of sleep apnea for VA compensation purposes. See March 2021 VA opinion. The Board acknowledges that the Veteran also has a diagnosis of insomnia; however, the Board finds that the Veteran's insomnia does not constitute a separate and distinct disability to warrant service connection. In this regard, the Board notes that the Veteran is service connected for major depressive disorder and the probative evidence shows that insomnia is one of his symptoms related to this disability. Specifically, the Board finds probative the September 2014 VA examiner finding that chronic sleep impairment is a symptom of the Veteran's diagnosed psychiatric disorder as well as the March 2021 VA opinion that the Veteran's insomnia is a manifestation of his service-connected psychiatric disability and does not constitute a separate and distinct disorder. The Board may not grant service connection for a symptom for which the Veteran is already being compensated. See 38 C.F.R. § 4.14 (pyramiding, or "the evaluation of the same manifestation under different diagnoses [is] to be avoided."). Additionally, while the Veteran was diagnosed with sleep paralysis in service, the Board does not find that the Veteran has a current diagnosis of sleep paralysis because none of the medical records throughout the pendency of the Veteran's claim reflect that he has current symptoms and/or a diagnosis of sleep paralysis and because the March 2021 VA examiner found that the Veteran did not have a current sleep paralysis disability. The Board finds that the March 2021 VA opinion is probative as to this matter because the VA examiner reviewed the entire claims file and provided rationale for this conclusion. Accordingly, the Board finds that the Veteran's diagnosis of OSA satisfies the first element of service-connection but that the Veteran does not have a current diagnosis of sleep paralysis nor is service connection warranted for the Veteran's insomnia, a symptom of his service-connected major depressive disorder. Second, the preponderance of the evidence is against finding that any sleep disability, to include sleep apnea, is related to service or is caused by, proximately, due to, or aggravated by any of the Veteran's service-connected disabilities. In this regard, the probative medical evidence of record does not indicate that his current sleep apnea is related to his time in service, to include his documented in-service sleep disturbances, insomnia, and/or sleep paralysis. The Board finds that the March 2021 VA opinion of record constitutes highly probative evidence of the medical nexus questions as this opinion was based upon a review of the Veteran's documented medical history, assertions, and other examinations of record, and is based upon rationale with clear conclusions and supporting evidence. See Nieves-Rodriguez v. Peake, 22 Vet. App. 295 (2008). Specifically, the March 2021 opinion sets forth, with detailed rationale, that the Veteran's sleep apnea was not caused by service, to include any presumed exposure to hazardous environmental toxins from service in Southwest Asia. The examiner specifically addressed the reasons for why the Veteran's in-service documented sleep disturbances and sleep paralysis are not related to his current OSA diagnosis and addressed his contentions concerning experiencing symptoms of sleep apnea, including why his reports of undergoing a sleep study in service and receiving CPAP treatment in or approximate to his discharge from service are not supported by the medical evidence of record. Further, while the medical evidence of record reflects complaints of insomnia and sleep disturbances related to such, the evidence does not show any complaints or symptoms triggering treatment or diagnosis of sleep apnea until several years after his active duty service. The Board notes that this delay, while not conclusive, weighs against the establishment of service connection. See Mense v. Derwinski, 1 Vet. App. 354, 356 (1991) (affirming Board's denial of service connection where veteran failed to account for lengthy time period between service and initial symptoms of disability). The Board also finds that the March 2021 VA opinion is probative evidence against finding that the Veteran's claimed condition is secondary to any of his service-connected disabilities because the VA examiner explained her reasoning with supporting medical evidence and literature. The Board also notes there is no contrary opinion of record. Additionally, the Board finds that there is no basis to find a link between the Veteran's service-connected disabilities and any obesity/weight-gain and, therefore, no basis to find that the Veteran's obesity or weight gain is an "intermediate step" between his service connected disabilities and his sleep apnea so as to permit service-connection on a secondary basis under 38 C.F.R. § 3.310(a). VAOPGCPREC 1-2017. In this regard, the Board also finds that the March 2021 VA opinion is the most probative evidence of record as to this matter and notes the Veteran has not argued, nor has the probative medical evidence of record raised, that his obesity/weight-gain is an "intermediate step" between a service-connected disability and his current sleep disability or that obesity/weight-gain is the cause of his sleep disability. The Board acknowledges that the Veteran is competent to report the symptoms that he experienced. However, while he asserts that he has a sleep disability that is attributable to service, there is no evidence to suggest that he is competent to provide an opinion as to the nature and cause of his disability or to opine that the symptoms that he experienced, as well as any in-service exposure, are related to specific diagnoses. These issues are medically complex, as they require specialized medical education and interpretation of medical test results. Jandreau v. Nicholson, 492 F.3d 1372, 1377 (Fed. Cir. 2007). As the Veteran is not shown to have appropriate training and expertise, he is not competent to render a persuasive opinion as to such matters. See id. Moreover, given that the medical professionals have not indicated that the Veteran's insomnia is a separate and distinct disability or indicated that that his diagnosed sleep apnea is related to service or his in-service sleep paralysis and sleep disturbances, the Board must rely on this competent medical evidence before it in deciding that service connection is not warranted. The Board gives the objective medical evidence significant weight in this regard and finds that the March 2021 opinion, which is supported by rationale, as well as the contemporaneous medical records to be of more probative weight than any lay assertions of the Veteran made in connection with his claim for service connection for this disability, including his statements that he was diagnosed with sleep apnea in and approximate to his discharge from service. Notably, and as discussed above, the Veteran's reports that he was diagnosed with sleep apnea in or approximate to service are not consistent with the contemporaneous medical records and, as such, are assigned less probative weight than the objective probative medical evidence, which weigh against a finding of continuity of relevant symptoms associated with his condition since service. Accordingly, when weighing the medical and lay evidence of record, including the contemporaneous medical records and the March 2021 opinion of record, the preponderance of the evidence shows that the Veteran's current sleep disability is not related to service, a service-connected disability, a service-connected disability resulting in obesity, nor any in-service injury, event, or disease, including presumed exposure to environmental hazards while serving in Southwest Asia. Finally, as noted above, as the Veteran's established sleep apnea is a diagnosed condition, and as the evidence reflects at a minimum at least a partially understood etiology, the Gulf War presumptions are not for application in this case. See 38 U.S.C. § 1117; 38 C.F.R. § 3.317 (defining qualifying chronic disease for purposes of Gulf War presumptions and stating when they are applicable, including that chronic multi symptom illnesses of partially understood etiology and pathophysiology, such as diabetes and multiple sclerosis, will not be considered medically unexplained). Therefore, the record does not show that the Veteran has a sleep disability, to include sleep apnea, that is related to service and/or secondary to his service-connected disabilities. As the weight of the evidence is against the claim, entitlement to service connection for a sleep disability, to include sleep apnea, is denied. 38 U.S.C. § 5107; 38 C.F.R. § 3.102; Gilbert, supra. MARJORIE A. AUER Veterans Law Judge Board of Veterans' Appeals Attorney for the Board Amanda Purcell, Associate Counsel The Board's decision in this case is binding only with respect to the instant matter decided. This decision is not precedential and does not establish VA policies or interpretations of general applicability. 38 C.F.R. § 20.1303.