While researchers had documented some of the behavioral contributors to fluctuation in individuals' lipid levels (e.g., nutrition patterns, smoking, exercise), little attention had been given to psychosocial stress. Early reports utilizing accountants, race car drivers, and air traffic controllers provided some uncontrolled data associating stress with cholesterol increases. Yet, no empirical research on stress that concomitantly examined other related influences was available. This paucity of data was probably due to lack of objective measures of stress and difficulty in measuring lipid subfractions.