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.

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.

Inclusion Criteria:

• Diagnosis for admission is acute myocardial infarction with severity between Killip I-III.
• Age is between 35-85.
• Participants who are willing to participate in the study and sign the informed consent.

Exclusion Criteria:

• Using sedative hypnotic drugs.
• Blindness or severe cataract.
• Neurological diseases such as epilepsy, brain injury, or stroke.
• Severe mental disorder such as major depressive disorder, bipolar disorder, schizophrenia, intellectual disability or substance use disorders.
• Unable to communicate.
• Participants who are unwilling to participate in the study or refuse to sign the informed consent.
• Participants who are not suitable to include in this study, evaluate by PI or Co-PI.