Scottish Longitudinal Study
Development & Support Unit

Completed Projects

Project Title:

Investigating the link between ‘light at night’ (light pollution) and the incidence of hormonal dependent cancers in the Scotland

Project Number:



Boris Portnov (University of Haifa, Israel)
Abraham Haim (University of Haifa, Israel)
Itai Kloog (University of Haifa, Israel)

Start Date:

Approved on 09-04-2008


A recent theory states that excessive exposure to light at night (LAN) may increase the risk of breast cancer. A variety of mechanisms have been proposed including suppression of melatonin secretion by the pineal gland leading to increased tumour growth, effects on immune and thermoregulatory functions and/or direct disruption of clock gene function in the suprachaismatic nuclei leading to alterations in cell cycle regulation in breast tissue.

A recent study we conducted in Israel concerning the relationship between LAN and breast cancer provided coherence of the previously reported case-control and cohort studies with the co-distribution of LAN and breast cancer in an entire population. The study revealed a clear connection between exposure to high LAN intensities and an increase in breast cancer rates. Since the results of the study are location specific the proposed follow up study will try and further validate the generality of our findings. In the proposed study we will attempt to investigate the links between local LAN levels in the Scotland and the incidence of hormonal dependent cancers, using cancer rates and LAN intensity data available for individual urban localities in the Scotland. A satellite image will be used as our primary data source for LAN and will be overlapped with various data layers including breast and prostate cancer rates (per 100,000 residents).

The research aims at investigating the association between exposure to light at night (LAN) and the incidence of hormone dependent cancers (mainly breast and prostate) in Scotland. Recent studies have reported that excessive exposure LAN may be a risk factor for breast cancer. Given the fact that the Melatonin (MLT) hormone has anti-prolific effect on cancer cells and that an excessive exposure to LAN reduces MLT plasma levels, it is expected that places with high LAN intensity in the UK will likely exhibit elevated cancer rates.



Davis, S., D. K. Mirick and R. G. Stevens (2001). "Night shift work, light at night, and risk of breast cancer." J Natl Cancer Inst 93(20): 1557-62.

Pauley, S. M. (2004). "Lighting for the human circadian clock: recent research indicates that lighting has become a public health issue." Med Hypotheses 63(4): 588-96.

Stevens, R. G. (1987). "Electric power use and breast cancer: a hypothesis." Am J Epidemiol 125(4): 556-61.

Stevens, R. G. (2005). "Circadian disruption and breast cancer: from melatonin to clock genes." Epidemiology 16(2): 254-8.

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