The investigators include 70 patients who are admitted to coronary care unit due to coronary artery disease, with severity between Killip I-III and age between 35-85. Participants are randomly assigned to 2 groups, the experimental group (blue light) and the placebo group (white light). Both groups receive light therapy or white light daily between 8am to 12pm. The investigators use actigraphy and heart rate variation analysis, and check melatonin level as objective measurements. The investigators use delirium scales to evaluate delirium and its severity. The light therapy is stopped once a participant is diagnosed of delirium or transferred, and the investigators keep following participants until discharge to evaluate the prognosis.
By using subjective and objective measurements, the investigators monitor the change of circadian rhythm in Intensive Care Unit (ICU) patients with acute myocardial infarction and the effect of light therapy.