It is shown in experimental investigations that variability of the task solution time (TST), intersystolic interval (ISI), pulse wave propagation time (PWPT), skin-galvanic reaction (SGR) decrease with an increase of the organism work tension. Specificity of the organism work tension in different analysis epochs (2 min, 30 min, 180 min) reflecting activity of inertia-different groups of regulator mechanisms in formation of dynamics of corresponding parameters is described. It is found that states of the organism in the "work-relax" terms differ most of all in changes of the decaminute variability of psychophysiological parameters (30- and 180-min analysis epochs), whereas information loading intensity differs in changes of a decasecond variability (2-min. epoch). It is shown that variability of TST and SGR of the 2-min analysis epoch and variability of ISI and PWPT of the 2- and 180-min epochs are the largest ones with different levels of the work tension. A significant expressiveness of 90-min-long periodicity of ISI, PWPT and sometimes of TST, SGR which exceeds expressiveness of quicker fluctuations is detected. A decrease of manifestation of naturally generated variability of psychophysiological parameters, including 90-min-long periodicity is connected with a decrease of rehabilitation processes in an organism. Under conditions of long-term (3h) continuous work the best productivity was revealed with a free work regime (in comparison with conditions of time scarcity and monotony), naturally generated variability of TST, including 90-min-long periodicity, being the most expressive.