SAN DIEGO — Higher levels of melatonin, a hormone involved in the sleep-wake cycle, may suggest decreased risk for developing advanced prostate cancer, according to results presented here at the AACR-Prostate Cancer Foundation Conference on Advances in Prostate Cancer Research, held Jan. 18-21.

Melatonin is a hormone that is produced exclusively at night in the dark and is an important output of the circadian rhythm, or the body's inherent 24-hour clock. Many biological processes are regulated by the circadian rhythm, including the sleep-wake cycle. Melatonin may play a role in regulating a range of other hormones that influence certain cancers, including breast and prostate cancers.

Exposing skin to sunlight may help to reduce blood pressure and thus cut the risk of heart attack and stroke, a study published in the Journal of Investigative Dermatology suggests.

Research carried out at the Universities of Southampton and Edinburgh shows that sunlight alters levels of the small messenger molecule, nitric oxide (NO) in the skin and blood, reducing blood pressure.

MINNEAPOLIS – Middle-aged men who drink more than 36 grams of alcohol, or two and a half US drinks per day, may speed their memory loss by up to six years later on, according to a study published in the January 15, 2014, online issue of Neurology®, the medical journal of the American Academy of Neurology. On the other hand, the study found no differences in memory and executive function in men who do not drink, former drinkers and light or moderate drinkers. Executive function deals with attention and reasoning skills in achieving a goal.

When it comes to global warming, there are seven big contributors: China is obviously number one, but exempt from climate treaties, as is India and Brazil. Also leading are the United States, gradually weaning itself off of the coal increases that occurred when environmentalists drove nuclear power from the country. Russia, Germany and the United Kingdom round the list out.

A new article in Environmental Research Letters blames these countries for more than 60 percent of pre-2005 global warming. Uniquely, it also assigns a temperature change value to each country that reflects its contribution to observed global warming.

If you have ever visited a doctor's office, there is a 50 percent chance you left feeling ashamed or guilty, according to psychologists from the University of California, San Diego. And what happened next? Perhaps you were motivated to make changes in an unhealthy behavior. Or, did you just lie to that doctor on subsequent visits? Avoid him or her? Maybe even terminate treatment entirely?

When E. F. Thompson stood on the deck of a ship cruise ship the Indian Ocean in the 1930s and observed a dolphin speed past the vessel in 7 seconds, he had no idea that this single observation would lead Sir James Gray to formulate the enduring paradox that bears Gray's name to this day. 

Based on Thompson's anecdote, Gray estimated the power required to propel the boisterous mammal through the waves at 20 knots (10.3 m/s) and concluded that the animal did not have enough muscle to pull off the feat. Puzzled by the paradox, Gray concluded that dolphins must use a trick of fluid mechanics to sustain the remarkable performance.