Circadian rhythms are pervasive processes through a range of body functions. While the earlier focus was on effect on sleep and performance, significant current interest is turning to the effects of circadian factors in metabolic and cardiovascular regulation. This review will address clinical and experimental data demonstrating metabolic and cardiovascular effects of circadian maladaptation. This maladaptation likely occurs as circadian stressors are extremely new on the evolutionary pressure/time scale-environmental light control, shift work and jet-lag effects did not previously exist.