Besides, the process of maladaptation or intolerance to shift work, that according to Haider et al (1988) may
develop through four phases of ‘adaptation’, ‘sensitization’,‘accumulation’ and ‘manifestation’, can have
different speed and intensity among the shiftworkers,so that the manifested complaints and/or illnesses can
appear in different periods of life, and this can further increase the high interindividual variability found in the
adverse effects of shiftwork.