Sunlight Exposure After Spinal Surgery

• Study objective: To assess how natural sunlight in hospital rooms affects psychosocial health, analgesic use, and medication costs for spinal surgery patients.

Methods

• Conducted a prospective study on 89 patients undergoing elective cervical and lumbar spinal surgery.
• Patients were housed on either the "bright" or "dim" side of the same hospital unit.
• Analgesic medication was standardized to morphine equivalents.
• Daily sunlight intensity was measured in each room.
• Psychologic questionnaires were administered post-surgery and at discharge.

Results

• Patients on the bright side had 46% more intense sunlight exposure (p = .005).
• These patients experienced less perceived stress (p = .035) and marginally less pain (p = .058).
• They used 22% less analgesic medication per hour (p = .047).
• They had 21% lower pain medication costs (p = .047).
• Age was inversely correlated with analgesic use (p <.001).
• Patients on the bright side used less analgesic medication across all age quartiles.

Implications of Sunlight and Light Exposure

• Artificial high-intensity light (phototherapy) or natural light can positively affect feelings and emotions.
• Effective for treating depression and seasonal affective disorder (SAD).
• Studies on refractory, bipolar, and SAD patients showed decreased length of stay (LOS) with increased light intensity.
• Associated with reduced depression in pregnant women, and reduced mortality from cancer.
• Reduced hospital mortality and LOS in patients experiencing myocardial infarction.
• Light exposure reduces activity of serotonin n-acetyltransferase, increasing serotonin, an inhibitor of pain pathways.

Methods Details

• Patients undergoing elective cervical and lumbar spinal surgeries were assessed for eligibility after admission.
• Exclusion criteria included discharge on day after surgery, major depression history, or antidepressant use.
• Single-occupancy rooms were used between March 12 and August 7, 2003.
• Of 147 patients approached, 46 declined and 12 were excluded.
• 89 patients participated with IRB approval and signed consent.
• Intent-to-treat model was used without dropping patients post-consent.
• Rooms were on the east (dim) and west (bright) sides of a corridor in Montefiore Hospital.
• An adjacent building blocked sunlight to east side rooms.
• Patients were assigned to rooms based on availability.
• Study personnel did not randomize and patients were blinded to the intervention and room assignment.
• Recruitment ended on August 7, 2003, due to unit relocation.
• Light intensity (lux) was measured twice daily, starting afternoon of post-operative day 1.
• Measurements were taken at approximately 9:30 AM and 3:30 PM.
• Doors were closed, artificial lights off, and blinds opened before measurement.
• Direct, reflective, and ambient sunlight were estimated using three measurements.
• Light meter (L-508Cine Zoom Master) was used at the center of the windowsill for direct measurement.
• Reflective measurement was taken at patient's eye level from the foot of the bed.
• Ambient measurement was taken next to the patient's head towards the window.
• Five readings per visit were averaged for direct, reflective, and ambient sunlight intensity.
• AM and PM sunlight intensities were calculated, multiplied by exposure hours, and summed daily.
• Analgesic use was the main outcome involving medication use per hour and pain medication cost per hour.
• Data was collected from registered nurses blinded to assignment, on all opioid and opioid-equivalent medications.
• Daily medication use was converted to oral morphine-equivalent (mg) using a standard method.
• The average analgesic medication use per hour (mg/hr) was calculated for each day and the entire stay.
• Hospital administrator, blinded to assignment, determined total pain medication cost per patient dividing by length of stay (LOS).
• Psychological and pain measures were derived from questionnaires administered on postoperative day 1 and discharge day.
• Subjective pain measured via the McGill Pain Questionnaire (MPQ).
• Depressive symptomatology measured by the Center for Epidemiological Studies Depression Scale (CES-D).
• Degree of perceived stress via the Perceived Stress Scale (PSS).
• Positive and negative affect measured using the Profile of Mood States (POMS) anxiety scale.
• Patients completed baseline questionnaires for initial pain score and dispositional optimism.
• Data analyses were performed using Minitab, using parametric and non-parametric tests.

Statistical and Group Methods

• Statistical significance was set at p < 0.05.
• A no-interaction group (N = 17; bright side = 10, dim side = 7) did not receive questionnaires, but pain scale was administered.
• The no-interaction group was included to measure possible effects of research staff contact.
• Primary outcome, pain medication use, was compared between the no-interaction group and other patients.
• Patient characteristics were similar in the bright and dim sides of the unit for demographics, clinical diagnoses, surgical procedures, baseline pain.
• The patients on the bright side of the unit received 46% more natural sunlight per day (p = 0.005).
• All patients wore identical hospital gowns, and room interiors were identical to eliminate confounding factors.

Further Results

• Patients on the dim side averaged 28.3% more opioid-equivalent medications per hour; p = .047.
• The patients on the dim side consistently required more analgesic medication each day
• No significant difference between groups related to prior or current usage of analgesic or non-analgesic medications.
• No significant difference in medication prescribed in OR/PACU or pain rating.
• Age was the only predictor of analgesic use.
• The largest statistically different effect in medication use was in the youngest age group.
• A 21% reduction in analgesic medication cost for the patients on the bright side (p = 0.047).
• Change from baseline stress scores and marginal decrease in pain in the bright side patients at discharge.
• Analgesic medication use was similar (p=0.9) in the no-interaction group and other patients, showing interaction did not influence results.

Study Conclusions

• Patients on the bright side received 46% more sunlight and needed 22% less analgesic medication.
• The patients on the bright side also had a 21% reduction in analgesic medication costs.
• Sunlight impacts postoperative analgesic medication use and should be replicated.
• Restricting the population, with small sample size are a limitation.

Limitations

• Methodology of sunlight measurement could not account for adjustments by patients.
• No biologic samples were collected.
• Unit director assigned patients without biometric considerations
• Age was determined to be a confounding factor.

Future Considerations

• Use sophisticated equipment to continuously monitor sunlight intensity.
• Take biologic samples (e.g., serotonin).
• Stratify patients before room assignment to remove age as confounding.

Broader Impact

• Influence of hospital environment relates to influence and healing process
• The impact of lighting may be considered in further studies, and facility design