Article

Melatonin, sleep disturbance and cancer risk

Laboratory of Chrono-Neuroendocrine Oncology, Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
Sleep Medicine Reviews (Impact Factor: 8.51). 08/2009; 13(4):257-64. DOI: 10.1016/j.smrv.2008.07.007
Source: PubMed

ABSTRACT

The pineal hormone melatonin is involved in the circadian regulation and facilitation of sleep, the inhibition of cancer development and growth, and the enhancement of immune function. Individuals, such as night shift workers, who are exposed to light at night on a regular basis experience biological rhythm (i.e., circadian) disruption including circadian phase shifts, nocturnal melatonin suppression, and sleep disturbances. Additionally, these individuals are not only immune suppressed, but they are also at an increased risk of developing a number of different types of cancer. There is a reciprocal interaction and regulation between sleep and the immune system quite independent of melatonin. Sleep disturbances can lead to immune suppression and a shift to the predominance in cancer-stimulatory cytokines. Some studies suggest that a shortened duration of nocturnal sleep is associated with a higher risk of breast cancer development. The relative individual contributions of sleep disturbance, circadian disruption due to light at night exposure, and related impairments of melatonin production and immune function to the initiation and promotion of cancer in high-risk individuals such as night shift workers are unknown. The mutual reinforcement of interacting circadian rhythms of melatonin production, the sleep/wake cycle and immune function may indicate a new role for undisturbed, high quality sleep, and perhaps even more importantly, uninterrupted darkness, as a previously unappreciated endogenous mechanism of cancer prevention.

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Available from: David E Blask, Oct 02, 2014
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    • "Given that one of the functions of the immune system is to recognize and eliminate altered cells including malignant ones [40], cancer resistance may have played a significant role in the evolution of sleep. Furthermore, variation in duration of the sleep/ wakefulness cycle strongly influences the production of various hormones including melatonin, which are important anti-tumor agents [57]. Sleep disturbances are very common in people affected by cancer [58, 59]. "
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    Full-text · Article · Feb 2016 · BioEssays
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    • "). In addition, suppression of melatonin caused by light exposure is dependent on the intensity and wavelength (Blask, 2009; Skene et al., 1999). Therefore, the health effects of ALAN are related to the exposure conditions and characteristics of the light, and not only to the amount of light. "
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    ABSTRACT: It has frequently been reported that exposure to artificial light at night (ALAN) may cause negative health effects, such as breast cancer, circadian phase disruption and sleep disorders. Here, we reviewed the literature assessing the effects of human exposure to ALAN in order to list the health effects of various aspects of ALAN. Several electronic databases were searched for articles, published through August 2014, related to assessing the effects of exposure to ALAN on human health; these also included the details of experiments on such exposure. A total of 85 articles were included in the review. Several observational studies showed that outdoor ALAN levels are a risk factor for breast cancer and reported that indoor light intensity and individual lighting habits were relevant to this risk. Exposure to artificial bright light during the nighttime suppresses melatonin secretion, increases sleep onset latency (SOL) and increases alertness. Circadian misalignment caused by chronic ALAN exposure may have negative effects on the psychological, cardiovascular and/or metabolic functions. ALAN also causes circadian phase disruption, which increases with longer duration of exposure and with exposure later in the evening. It has also been reported that shorter wavelengths of light preferentially disturb melatonin secretion and cause circadian phase shifts, even if the light is not bright. This literature review may be helpful to understand the health effects of ALAN exposure and suggests that it is necessary to consider various characteristics of artificial light, beyond mere intensity.
    Full-text · Article · Sep 2015 · Chronobiology International
    • "In connection with disease and/or bodily injury, the body has an increased need for sleep. Sleep deprivation is associated with several diseases and increased mortality (Blask 2009, Bollinger et al. 2010). "
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    ABSTRACT: Aims and objectivesThe aim was to describe nurses' experiences of patients' sleep at an emergency hospital and their perceptions of sleep-promoting interventions.Background Promotion of patients' sleep during hospital care is an important intervention for the nursing profession. To promote sleep and to initiate sleep-promoting interventions, nurses need basic knowledge about sleep and its physiology. Therefore, it is of importance to explore and expand knowledge about how nurses experience patients′ sleep and how they perceive working with it while providing care.DesignA qualitative descriptive design was used.Methods Data were collected from four focus groups and seven individual interviews. A total of twenty-two registered nurses participated. Data were analysed using a qualitative content analysis.ResultsNurses expressed a desire and an ambition to work in ways that promote patients' sleep during hospitalisation. Nurses reported that health care services and emergency hospitals were not organised according to patients' perspective and needs. Furthermore, they did not have opportunities to work effectively to promote sleep according to the patients' wishes. Several nurses stated that they did not have sufficient knowledge about sleep and that they did the best they could under prevailing circumstances. Nurses emphasised the importance of sleep for patients and that it was an area that should be given far greater priority.Conclusions The results indicate that nurses currently have insufficient knowledge about sleep and sleep-promoting interventions. These aspects of nursing is based on personal experience and common sense rather than being evidence based. Furthermore, sleep as a nursing topic needs to be developed and given more focus in order for nurses to be able to deliver high quality care at emergency hospitals.Relevance to clinical practiceNurses require more knowledge and education to gain deeper understanding of sleep and to deliver evidence-based, high quality care.
    No preview · Article · Sep 2015 · Journal of Clinical Nursing
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