melatonin

Night light exposure could make breast cancer tumors tamoxifen resistant

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Tamoxifen is an estrogen-blocking medication typically used to treat breast cancer that has spread to other parts of the body. But new research conducted in rats suggests exposure to dim light at night – as little as that coming in a window from a street light – suppresses melatonin production, making tumors resistant to the drug.
dim indoor lamp
Researchers found that exposure to dim light at night results in breast cancer tumors becoming resistant to tamoxifen.

The study, led by Prof. Steven M. Hill of Tulane University School of Medicine in New Orleans, LA, is published in Cancer Research, a journal of the American Association for Cancer Research.

“Our levels of melatonin are not determined by sleep, as many people think,” explains Prof. Hill. “It is actually the darkness that is important. During the night, if you sleep in a brightly lit room, your melatonin levels may be inhibited; however, if you are in the dark but cannot sleep, your melatonin levels will rise normally.”

He and his team note that disruption of circadian rhythms by night shift work or disturbed sleep could result in an increased risk of breast cancer and other diseases. For patients with hormone receptor-positive breast cancer, Prof. Hill adds that tamoxifen resistance “is a growing problem.”

Read full article at MNT

The Relationship Between Obesity and Exposure to Light at Night: Cross-Sectional Analyses of Over 100,000 Women in the Breakthrough Generations Study

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There has been a worldwide epidemic of obesity in recent decades. In animal studies, there is convincing evidence that light exposure causes weight gain, even when calorie intake and physical activity are held constant. Disruption of sleep and circadian rhythms by exposure to light at night (LAN) might be one mechanism contributing to the rise in obesity, but it has not been well-investigated in humans. Using multinomial logistic regression, we examined the association between exposure to LAN and obesity in questionnaire data from over 100,000 women in the Breakthrough Generations Study, a cohort study of women aged 16 years or older who were living in the United Kingdom and recruited during 2003–2012. The odds of obesity, measured using body mass index, waist:hip ratio, waist:height ratio, and waist circumference, increased with increasing levels of LAN exposure (P < 0.001), even after adjustment for potential confounders such as sleep duration, alcohol intake, physical activity, and current smoking. We found a significant association between LAN exposure and obesity which was not explained by potential confounders we could measure. While the possibility of residual confounding cannot be excluded, the pattern is intriguing, accords with the results of animal experiments, and warrants further investigation.

 

American Journal of Epidemiology

 

‘Arrogance’ of ignoring need for sleep

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Society has become “supremely arrogant” in ignoring the importance of sleep, leading researchers have told the BBC’s Day of the Body Clock.

Scientists from Oxford, Cambridge, Harvard, Manchester and Surrey universities warn cutting sleep is leading to “serious health problems”.

They say people and governments need to take the problem seriously.

Cancer, heart disease, type-2 diabetes, infections and obesity have all been linked to reduced sleep.

The body clock drives huge changes in the human body.

It alters alertness, mood, physical strength and even the risk of a heart attack in a daily rhythm.

 

BBC

How Much Sleep Do You Really Need, And Why?

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Leonardo Da Vinci is said to have been a so-called polyphasic sleeper, arranging his life around an endless series of catnaps. What’s arguably more relevant in 2014, however, is Cosmo Kramer’s attempt to adopt the master’s rest schedule in the classic episode ofSeinfeld. Bear with me.

 

Read the full story at  Medical Daily