This is an appeal from an order of the Industrial Commission which denied claimant Cox an award for total permanent disability. Claimant asserted before the Commission that she was totally and permanently disabled by reason of “post-traumatic stress syndrome” which resulted from her employment with her employer, Denny’s Restaurants. The Commission, however, found that her mental and emotional problems were not a result of stress resulting from or relating to her employment, but rather that claimant suffered from a histrionic personality disorder and a situational adjustment disorder which were not related to or a result of her employment with Denny’s Restaurants. The Commission also held that emotional and mental problems allegedly caused by job stress but unaccompanied by a physical injury do not constitute a compensible injury under our statutory scheme. We affirm the Commission’s findings and conclusions relating to the lack of causal connection between claimant’s employment and her disability. Hence, it is unnecessary to rule upon the Commission’s conclusion relating to the noncompensability of a disability allegedly resulting from job stress-related emotional and mental disabilities.
Claimant Cox was born in 1954 and began working intermittently for Denny’s as a waitress and a hostess when she was 16. She left employment with Denny’s in 1974 and worked for several employers both in and out of the restaurant business until 1977 when she went back to work at Denny’s. She entered the company’s management training program in January of 1978 and became an assistant manager in April 1978. In January 1979 she became a manager and continued in that position until July 31, 1980. As manager she earned $324.00 per week and was eligible for bonuses which were dependent upon sales and costs.
The essential thrust of this appeal is the assertion by claimant Cox that the findings of the Commission of a lack of causal relationship between claimant’s employment *323and her mental and emotional problems are not supported by the evidence. Cox asserts that for a period of time when the restaurant had insufficient employees she was required to work 80-100 hours per week, which coupled with a sexual relationship with her district manager, directly caused her mental problems. Cox also asserts that the Commission erred in relying upon the testimony of only one of the several mental health professionals who testified, since that psychiatrist was only retained by the surety to examine the claimant and was not one of the treating physicians.
The record indicates that Denny’s Restaurants are a chain operation and are generally staffed by a manager and two assistant managers. In some individual restaurants, however, the financial condition was deemed not to justify two assistant managers, and in such units non-management personnel would be designated as “key persons” or “unit aides” and would function somewhat as an assistant manager. The Boise Denny’s Restaurant did not justify two assistant managers.
Denny’s Restaurants operate 24 hours a day in three shifts: 7 a.m. to 3 p.m., 3 p.m. to 11 p.m., and 11 p.m. to 7 a.m. In the Boise restaurant the manager would work during the days and the assistant manager would work during the swing shift and into the graveyard shift. When the manager or assistant manager was not on duty the “key person” would be responsible for managerial duties.
In January 1979, when Cox became manager of the Boise restaurant, she had an assistant manager and a management trainee. From April to August 1979, the restaurant operated with two assistant managers. From August 1979 through 1980 the Boise restaurant operated with Cox as manager and one assistant manager. On June 13,1980, the assistant manager received a leave of absence until June 19, and again from June 24 to July 11, 1980. On July 31, 1980, claimant Cox attempted suicide, and she has not worked for Denny's since that incident.
It was during the time that the assistant manager was on leave during parts of the months of June and July 1980, that claimant asserts that she worked between 80-120 hours per week. It is clear from the decision of the Industrial Commission that the Commission did not assign credibility to the evidence presented by claimant Cox in support of that assertion. The Commission found that claimant Cox was not required to work 80-120 hours a week during the absence of the assistant manager. The Commission noted that claimant Cox did not keep a time card, that there was no unusual surge of business activity requiring extraordinary hours on the part of Cox, that there was available personnel and man hours per shift to do the work, that when claimant Cox was absent from the restaurant for a week during May the assistant manager adequately managed the restaurant, putting in approximately 70 hours per week, and that claimant Cox did not work at all times when she was in the restaurant but spent hours there which were not required. All of those findings of the Commission are supported by substantial competent, although conflicting evidence, and hence will not be disturbed. I.C. § 72-732(1); Burn v. Nyberg, 108 Idaho 151, 697 P.2d 1165 (1985). The credibility of witnesses is for the Commission to determine since the Commission has the opportunity to observe their demeanor. Houser v. Southern Idaho Pipe and Steel, Inc., 103 Idaho 441, 649 P.2d 1197 (1982). The Industrial Commission is the final arbiter of conflicting evidence. Hayes v. Amalgamated Sugar Co., 104 Idaho 279, 658 P.2d 950 (1983), Nelson v. Pumnea, 106 Idaho 48, 675 P.gd 27 (1983). See also I.C. §§ 72-724, -732; Curtis v. Shoshone Sheriffs Office, 102 Idaho 300, 629 P.2d 696 (1981).
Cox also asserted that the investigation of a complaint filed by her assistant manager caused her additional undue stress. Denny’s management policy was that of open communication between the district office and individual restaurants to insure the complaints of non-management *324and assistant management personnel could be thoroughly investigated. The record indicates that such a complaint was lodged against claimant Cox by her assistant manager, was investigated, and that she acknowledged certain violations of company policy but was retained in her employment as manager of the restaurant. There is nothing in the record to indicate that Denny’s policy was unusual or that the lodging of the one complaint led to any undue stress on claimant Cox.
Claimant Cox also asserts that a contributing factor to her mental and emotional problems was her sexual relationship with her district manager. The Commission found that Cox and the district manager had engaged in sexual relations on two occasions in January and February 1980. It is Cox’s assertion that the district manager got her intoxicated to the point that she would indulge in sexual relations. However, the Commission found that the established sexual relationship was not the cause of her mental and emotional problems. The record clearly shows that the claimant had been a victim of incest early in her life, that she had quit school at the age of 15 and was on probation until age 18, that she left home to travel with a musician at age 19 by whom she became pregnant and returned home to bear her child in 1974. She then obtained employment and became pregnant by a fellow employee. She married her first husband while she was approximately two months pregnant, and at his insistence obtained an abortion. The testimony of one of the psychiatrists indicated that a post-traumatic stress disorder has to be an experience that is out of the usual human experience or totally dystonic, which means foreign to the person. Given Cox’s previous sexual experience, the two isolated sexual experiences with her district manager could hardly be said to have been outside the realm of her usual human experience, and hence the Commission’s finding of the lack of relationship between the sexual incidents and her mental illness is supported by substantial competent evidence and will not be overturned.
Claimant Cox next asserts that the Commission erred in finding that she suffered from a histrionic personality disorder and a situational adjustment disorder rather than a post-traumatic stress syndrome from which Cox argues she suffered and continues to suffer.
The Commission found that Cox does not have a physical disorder as a result of her emotional problem, nor are her emotional problems related to a physical disorder. The record supports that finding. However, there is little doubt that claimant Cox has suffered from emotional and mental problems. On July 29, 1980, she began treatment with a psychiatrist, and on July 31,1980 attempted suicide. As a result she remained hospitalized for psychiatric care for approximately two weeks and continued treatment as a outpatient until October 8, 1980. In July 1981 claimant underwent further psychological and psychiatric treatment and was rehospitalized for such care for approximately two weeks. Thereafter she received additional therapy until February 1, 1982. During February claimant was rehospitalized for psychiatric care in Anchorage, Alaska, and thereafter received psychiatric outpatient treatment for approximately four months. Claimant was rehospitalized in Boise during May and June 1983, and during July of 1983 was rehospitalized in Alaska following which she was treated as an outpatient until May of 1984. At least six mental health professionals have treated claimant between the time of her initial suicide attempt and the hearing before the Commission. Among the evidence tendered by expert witnesses, were at least five different diagnoses.
The Commission, in its findings, clearly relied on and essentially adopted the testimony, diagnosis and conclusion of Dr. Holt, a psychiatrist, and rejected the testimony and conclusions of the other testifying mental health professionals. Claimant Cox asserts that such action and the findings of the Commission are therefore erroneous and argues that Dr. Holt’s testimony should be rejected since he was the *325only expert witness who had not actually treated the claimant between the time of her suicide attempt and the hearing before the Commission, but had merely examined her at the request of the surety.
Dr. Holt’s testimony indicated wide experience and expertise in treating post-traumatic stress in Veterans Administration hospitals with Viet Nam veterans and ex-prisoners of war. He testified that post-traumatic stress is caused by an experience that is totally dystonic or outside the realm of usual human experience. After reviewing the volumnous medical records and conducting his own examination and psychological testing of the claimant, he concluded that she did not fit the diagnosis of post-traumatic stress syndrome. Rather, he diagnosed her as suffering from a histrionic personality disorder which was formed early in life and was characterized by violent mood swings and a princess-victim-rescuer pattern of behavior. Histrionics, he stated, are prone to suicide attempts which are not typical of those who suffer from post-traumatic stress syndrome, who rarely attempt suicide. He noted that claimant had twice attempted suicide and been through three very bad marriages. He testified that entering into a marriage after a suicide attempt and failed employment is the typical princess-victim-rescuer behavior of the histrionic.
Dr. Holt testified that the histrionic personality disorder of the claimant developed early in life and was undoubtedly fully formed as a teenager, and hence something from which the claimant suffered before her employment with Denny’s. Dr. Holt testified that claimant also suffered from a situational adjustment disorder which he opined resulted from stresses from outside her employment. The testimony indicated that claimant suffered considerable stress during mid-1980 while she was living with her son. Her mother moved into the household and disapproved of the way in which she was raising her son, and disapproved of claimant’s fiancee. Her mother moved out of the household, but immediately next door, and her fiancee moved in with the claimant bringing his mother and sister with him. Fellow workers testified as to the stress that claimant was suffering from those non-employment related pressures.
Claimant is correct in her assertion that there was wide diversity among the expert testimony of the mental illness from which she suffered, and the causal relationship, if any, between that mental illness and her employment with Denny’s. However, those differences in diagnoses, and as to causation, standing alone are of no avail to claimant since the Commission is the arbiter of such conflicting evidence, and its determination as to the weight and credibility of the testimony is conclusive upon appeal unless it is clearly erroneous. We do not conclude that the Commission’s reliance upon, and essential adoption of the testimony of Dr. Holt, was clearly erroneous. As this Court has stated in House v. Southern Idaho Pipe and Steel, Inc., 103 Idaho 441, 649 P.2d 1197 (1982) and Arnold v. Splendid Bakery, 88 Idaho 455, 401 P.2d 271 (1965):
The fact that a greater number of witnesses supported a view different from the conclusion reached is of no moment in determining the preponderance of the evidence. Rather, the determination must be based on an assessment of the reliability, trustworthiness and probative value of the evidence. As such, the determination is in the first instance a question of fact committed to the particular expertise of the Commission; and its determination as to the weight and credibility of the testimony is conclusive on appeal unless it is clearly erroneous.
We hold that the findings of the Commission are based upon substantial competent evidence and they will not be overturned. The Commission found that claimant Cox’s mental illness was not employment related and hence, we deem it unnecessary to decide in this case whether stress-related emotional disorders which are caused by employment are compensable. The decision of the Industrial Com*326mission is affirmed. No costs or attorney fees on appeal.
DONALDSON, BAKES and HUNTLEY, JJ., concur.