Effect of Green Light Exposure at Different Times on the Pain of Subjects

Random numbers were generated by the computer to randomly assign patients who met the inclusion and exclusion criteria to the experimental group (exposed to green light) and the control group (exposed to transparent light). The patients were randomly assigned to three time periods (8:00-9:00, 12:00-13:00, 16:00-17:00) to receive a colored exposure with glasses: Therefore, in order to minimize bias and expectations, it was not informed to the patients which color would affect the pain during the arterial puncture. The patients rested in the pre-anesthesia room for 5 minutes, their heart rate (HR) was measured, and a pain sensitivity test (tender point) was conducted. Then, the patients wore the trial glasses and stayed in the pre-anesthesia room for 30 minutes, and they underwent arterial and venous punctures. While monitoring the patients' heart rate, the catheterization of the arterial and venous punctures was performed. Then, during the arterial and venous puncture, their pain scores (NRS) were recorded separately.

exposed to green light (green group) for 30 minutes. The above operation will be repeated to measure the patient's pain threshold.

Inclusion criteria

• Age range: 18 - 50 years old.
• ASA classification: I - III.
• Planned to undergo abdominal surgeries requiring general anesthesia and arterial puncture (this is not necessary for the healthy volunteer group).
• Obtained informed consent from the patients.

Exclusion criteria

• Skin ulceration, allergic reactions, or dermatitis at the tested area.
• Long-term use of analgesics or psychiatric medications.
• History of color blindness or uncorrected cataracts.
• Severe cardiovascular or respiratory diseases, inflammatory disorders, etc.
• Failure of the first arterial puncture.
• Communication difficulties, etc.