Summer Sunshine and Health:  The Good, the Bad and the Ugly

Ben Adkins, MD

            As the summer season begins, one of the things that we can look forward to is bright, sunny days full of fun outdoor activities.  Sunlight, in addition to sustaining all life on the planet, affects our health in both positive and negative ways.  Here are some guidelines on how to enjoy the sun safely, with a discussion of The Good, The Bad, and The Ugly of sunshine (with apologies to Mr. Eastwood).

Stronger bones:  Sunlight allows the skin to make vitamin D.  The time required is at least 15 minutes per day (over a skin area about as big as the face) to meet the daily requirements.  During the winter in northern climates, many people do not meet their vitamin D requirement and bone density decreases slightly.  Summer sunshine allows bone density to recover, which reduces risk of osteoporosis and fractures.

            Better mood:  Seasonal Affective Disorder (SAD) resembles depression, and is linked to decreased sunlight levels in wintertime.  For those with symptoms of depression during the winter, the advent of summer can greatly improve emotional health.  Sunlight may enhance the benefits of antidepressant medications.  Some researchers believe that appropriate levels of summer sunshine can even improve serotonin levels in the brain the following winter, reducing the risk of SAD. 

            Sun exposure has a long list of risks, which means that the only truly “safe tan” comes from a bottle.  Some of the risks include the following:

Immediate illness:  Excessive sun exposure may cause fatigue, dehydration, heat exhaustion and heat stroke.  Avoiding prolonged outdoor exercise when the temperature rises can minimize the risk of these problems.  It takes about 3 weeks for your body’s cooling systems to adjust to a change in climate, so the risk of heat-related illness is higher during the first part of the summer. 

            Sunburn:  In the summer, a sunburn can occur in under 20 minutes.  Sunburn occurs when solar radiation causes immediate damage, leading to inflammation of the skin.  Mild sunburns cause redness and pain, more serious sunburns may lead to blistering and increased risk of melanoma.  Severe sunburn can cause dehydration, and occasionally serious illness.  Some early signs of a serious sunburn include chills, fever, confusion, and nausea.

Cataracts:  Over a lifetime, excessive sun exposure causes clouding of the lens of the eye.  The risk of this condition can be reduced by always wearing sunglasses that block ultraviolet radiation during outdoor activities.  Fortunately, cataracts can be cured by surgery. 

            Macular Degeneration:  This disease of the retina of the eye causes irreversible blindness, and unlike cataracts, there is no cure.  Blocking ultraviolet radiation by wearing sunglasses is one of the few ways to reduce the risk of this common condition.  (Another risk factor is smoking)

Skin Aging:  Any suntan is evidence that damage has occurred to skin cells and their DNA, which eventually produces breakdown of the collagen supporting the skin (also known as wrinkles).  Pigmented spots called lentigines and ephelides (freckles) follow.  Some repair of damage can occur, but the aging of the skin is cumulative, and directly related to the lifetime amount of sun exposure.  

The Ugly

Three types of skin cancer are caused by sun exposure.  These are basal cell cancer, squamous cell cancer, and melanoma.  Of these, basal cell is the most common, with 500,000 new cases annually, and can be cured by surgery.  Squamous cell is also common, causing 100,000 new cases, and can also be cured if caught early.  Melanoma causes 30,000 to 50,000 new cases each year, and is more deadly.  About 1 in 80 people will develop melanoma.  The risk of melanoma has increased several fold over the past half-century, which may be due to the declining ozone layer.  Melanoma risk increases with any tanning, and especially with any blistering sunburn.  The warning signs of any skin cancer may be remembered as “ABCD”.  These are Asymmetry, Border irregularity, Color variations, and Diameter bigger than a pencil eraser.  A simpler rule to remember is that any changing skin lesion may be a warning sign. 

Summary

Sunlight has some health benefits when enjoyed (like anything good) in moderation:  15-20 minutes per day is safe for most people, especially if sunscreen is used.  The best time to be outdoors is before 10:00 a.m. or after 4:00 p.m.  Children should wear sunscreen daily.  Sunscreens with a sun-protection factor of 30 or higher are best.  Wearing long-sleeve shirts and sunglasses with UV-absorbing lenses also helps.  See your doctor if you notice any changing skin spot.

Rakel: Conn's Current Therapy 2004, 56th ed., Copyright © 2004 Elsevier