In Pain? Move to the Sunny Side!

Summarized by Robert W. Griffith, MD
September 2, 2005

Introduction

Sunlight is known to have positive effects - it can lift depressed moods, reduce cancer mortality, and shorten hospitalization after a heart attack. A new study from Pittsburgh has shown its effect on the need for anti-pain medication. The findings are reported in Psychosomatic Medicine, and summarized below.

What was done

Patients undergoing neck or spinal surgery were recruited. They were treated postoperatively in a hospital unit that had two sides - "bright" and "dim" - according to the direction of the sun. The patient rooms were all of the same size and configuration. Patients were assigned to rooms based on room availability.

Light intensity was measured twice a day at 9:30 am and 3:30 pm with window blinds opened to allow maximum sunlight into the room.

All analgesics were given 'as required' by the nursing staff. During the first 24 hours on the unit, the patients could self-administer their analgesic medication. In order to be able to compare the results for different patients, the doses of all analgesics were converted to standard morphine equivalents. The average analgesic use per hour was calculated for each patient's stay.

Questionnaires were administered to patients on their first postoperative day and their discharge day. They covered pain, depression symptoms, perceived stress, and anxiety.

What was found

The patients recovering on the bright side of the unit were exposed to 46% more sunlight, on average, than those on the dim side. They reported less stress, and marginally less pain. When it came to analgesic use, it was found they took 22% - almost a quarter - less pain medication per hour than those on the dim side.

The reduced analgesic use translated into reduced medication costs. There was a 21% reduction in medication cost for those patients on the sunny side of the unit.

Conclusions

In view of the generally accepted beneficial effects of sunlight on spirit and mood the results of this study are not too surprising. However, they show that it's more than just 'all in the mind'. The reduced analgesic intake on the bright side of the hospital unit translated into relevant reductions in medication costs.

It should be noted that the actual effect may have been greater than that measured. The patients' actual exposure to sunlight could have been influenced by the drawing of window blinds, which was not assessed in the study - light was measured twice daily with maximum exposure.

Why did this difference occur? It's likely that the mechanism responsible for the effect seen was related to blood serotonin levels. Light increases these levels, and serotonin inhibits pain pathways in the brain and spinal cord. (In a similar way, some antidepressant medications exert their effect by boosting circulating serotonin levels.)

Are there practical implications? Not many, really. One might expect architects to design hospitals so that they aren't blocked from the sun by other buildings, and, if you're given a choice, select the sunny side of the unit. And, keep the blinds open!

Source

• The effect of sunlight on postoperative analgesic medication use: a prospective study of patients undergoing spinal surgery. JM. Walch, BS. Rabin, R. Day,  et al., Psychosomatic Medicine, 2005, vol. 67, pp. 156--163

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