Effect of sunlight exposure on mortality

Project details:

In October 2023, NIHR asked Bristol ESG to undertake a systematic review to examine the overall effect of sunlight on population mortality, to inform sun safety advice and help people to find the right balance between gaining the benefits of sunlight exposure whilst avoiding the risks.

The review is funded by the NIHR Evidence Synthesis Programme (project number: NIHR161983) and is registered with PROSPERO (CRD42023474157).

Project status: completed

What is the problem? 

Being outside in direct sunlight is known to cause damage to our skin. Being sunburnt can increase the chance of getting skin cancer. In fact, sunlight is one of the main causes of cancer. Because of this, sun safety advice in the UK is mainly focused on avoiding the harmful impacts of sunlight. Organizations that provide advice on keeping safe in the sun, such as the British Skin Foundation, say that you should aim to stay in the shade between 11am and 3pm and wear clothing that covers as much skin as possible.

There are also positive effects of sunlight exposure. Sunlight has been shown to increase the amount of vitamin D your body produces. Vitamin D is important for our health. It is not only good for our bones; it may also help our immune system and reduce our risk of developing cancer. Recently, researchers have suggested that sunlight might have other health benefits including reducing the risk of dying from cardiovascular disease.

We also know that different skin types react to sunlight in different ways. People with darker skin need more exposure to sunlight than people with lighter skin to produce the same amount of vitamin D. On the other hand, people with darker skin might have less risk of developing sun-related skin cancer. However, sun safety advice in the UK doesn’t tend to account for differences in skin type.

What are we trying to find out? 

We aim to gather all the available studies that have measured both sunlight exposure and mortality (death) rates. We are interested in the overall number of deaths (by any cause), as well as deaths specifically caused by cardiovascular disease or cancer. By combining the findings of these studies, we hope to find out whether long-term sunlight exposure increases or decreases our risk of dying.

Contact: bristol-esg@bristol.ac.uk