NTERNATIONAL R EVIEW OF I NDUSTRIAL AND O RGANIZATIONAL P SYCHOLOGY 2005 Sleep disturbances

286 I NTERNATIONAL R EVIEW OF I NDUSTRIAL AND O RGANIZATIONAL P SYCHOLOGY 2005 Sleep disturbances

Findings from a study of blue-collar workers (Melamed et al., 1999), in which a version of the SMBM was used, provided evidence supporting the notion that burnout is associatedwith increasedsomatic andphysiological hyper-arousal. Among those reporting higher levels of burnout, there was a higher prevalence of unpleasant sensations of tension andrestlessness at work, post-work irritability, sleep disturbances, complaints of waking up exhaustedandhigher cortisol levels during the workday (Melamedet al., 1999). A recent study (Grossi et al., 2003) reported that all three measures considered here—the MBI, SMBM, and VE—were closely associated with sleep disturbances. These findings suggest that burned-out persons may have an inability to unwindafter working hours. Furthermore, these persons may suffer from insomnia andnonrefreshing sleep. This may explain in part the chronic fatigue experiencedby burned -out persons. Insomnia in general (Carney, Freedland, & Jaffe, 1990; van Diest, 1990), and waking up exhaustedin particular (Appels & Schouten, 1991), were foundto be risk indicators of future myocardial infarction. Therefore, the findings of this study suggest an additional pathway by which burnout may be associated with increasedrisk of CVD.

The metabolic syndrome The metabolic syndrome is considered a major risk factor for heart disease,

andinclud es five components that tendto co-occur: obesity (especially abdominal obesity), dyslipidemia (especially high levels of triglycerides and low levels of high-density lipoprotein cholesterol), and elevated levels of glucose andbloodpressure (Meigs, 2003). While there is no consensus regarding the specific clinical thresholds for establishing a medical diagnosis for each of these components, the presence of three or more of the above components is considered as elevated risk for heart disease. Burnout has been foundto be associatedwith some of the components mentionedabove. In a study of 104 disease-free male employees of a high-tech company, Melamed, Kushnir, andShirom (1992) foundburnout to be correlatedwith elevated risk factors for cardiovascular disease. Specifically, this study reported that the combination of high burnout andtension was significantly associated with increasedtotal cholesterol, Low Density Lipoprotein (LDL), triglycer- ides, and uric acid, and marginally with ECG abnormality, though no association was foundfor systolic anddiastolic bloodpressure. In another study of healthy employees (Shirom, Westman, Shamai, & Carel, 1997), burnout in men was found to be predictive of cholesterol changes, evidenced 2–3 years later. In this prospective research, among female employees emotional burnout was positively correlatedbut physical fatigue was nega- tively correlatedwith cholesterol andtriglyceride levels (Shirom et al., 1997).

B URNOUT AND H EALTH R EVIEW

Inflammation biomarkers Following the evidence that classical risk factors for CVD (hypertension,

poor lipids profile, smoking, lack of physical exercise, and obesity) only in part explain the incidence of myocardial infraction, new research efforts have been investedin identifying alternative risk factors for CVD. Accumulating evidence indicates that there is a link between inflammation, atherosclerosis, and acute coronary syndromes (Koenig, 2001; Libby, Ridker, & Maseri, 2002; Ross, 1999). There is evidence supporting the relationships between markers of inflammation, abnormalities of glucose metabolism, andCVD end points (Resnick & Howard, 2002). Moreover, it is now widely recognized that psychological stress may induce inflammatory reactions similar to those evokedby infection, trauma, andtissue damage (Maier & Watkins, 1998). Repeated episodes of acute psychological stress may induce chronic inflam- matory processes (for recent reviews see Black, 2002, 2003; Black & Garbutt, 2002; Kop, 2003). Since chronic psychosocial stress at work is a well- establishedanteced ent of burnout (Schaufeli & Enzmann, 1998), the elevation of inflammation biomarkers couldbe a pathway through which burnout affects CVD.

Findings from the study by Lerman et al. (1999) suggest that burnout may be associatedwith an inflammation biomarker. In this stud ya significant association was uncoveredbetween burnout andLeukocyte Adhesiveness/Aggregation (LAA), a sensitive marker for the detection of inflammation andassessment of its intensity (Rotstein et al., 2002). The search for LAA as a marker of inflammation was basedon the notion that white bloodcells become activatedandsticky d uring the inflammatory response (Frenette & Wagner, 1996a, 1996b). LAA probably represents both enhanced expression of cell adhesion molecules during cell activation, as well as the appearance of plasmatic adhesive proteins during the acute phase response (Rotstein et al., 2002). Additional evidence indicates a high correlation between LAA anderythrocyte aggregation (Shapira et al., 2001), andthere is evid ence of redbloodcell aggregability in patients with hyperlipidemia, diabetes mellitus, hypertension, and acute myocardial infarction (Berliner, Zeltser, Rotstein, Fusman, & Shapira, 2001; Shapira et al., 2001). Using the SMBM andother burnout measures, Grossi and his colleagues (Grossi et al., 2003) foundthat among 63 apparently healthy