Archive for February 12th, 2013

February 12, 2013

Melatonin

Melatonin [mel-uh-toh-nin] is a naturally occurring hormone found in animals, plants, and microbes. In animals, circulating levels of melatonin vary in a daily cycle, thereby allowing the entrainment of the circadian rhythms of several biological functions.

Many biological effects of melatonin are produced through activation of melatonin receptors, while others are due to its role as a pervasive and powerful antioxidant (a molecule that neutralizes free radicals), with a particular role in the protection of nuclear and mitochondrial DNA. Products containing melatonin have been available over-the-counter in the United States since the mid-1990s. In many other countries, the sale of this neurohormone is not permitted or requires a prescription.

read more »

February 12, 2013

Dark Therapy

Sleep hygiene

Dark therapy is an experimental treatment which involves eliminating all light in the subject’s environment, for a period of six to sixteen hours per day, in combination with a regular sleep schedule. Dark therapy manipulates circadian rhythms acting on hormones and neurotransmitters. It has been proposed recently (2005) to combine the chronobiological manipulations of light/dark and/or sleep/wake therapies with psychopharmacological medication.

In the words of Swiss neuroscientist Anna Wirz-Justice: ‘Light therapy has undergone widespread controlled randomized clinical trials, and wake therapy has been so widely studied over decades that the efficacy data are strong. These nonpharmaceutical, biologically based therapies are not only powerful adjuvants, but also antidepressants in their own right… [P]ilot studies suggest that the simple measure of promoting long nights (more rest, more sleep, no light) can stop rapid cycling in bipolar patients, or diminish manic symptoms — intriguing findings that require replication.

read more »

February 12, 2013

Spandrel

In evolutionary biology, a spandrel [span-druhl] is a a characteristic that did not originate by the direct action of natural selection, that was later co-opted for a current use. The term was coined by the Harvard paleontologist Stephen Jay Gould and population geneticist Richard Lewontin in their influential paper ‘The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Program’ (1979).

In their paper Gould and Lewontin employed the analogy of spandrels in Renaissance architecture: curved areas of masonry between arches supporting a dome that arise as a consequence of decisions about the shape of the arches and the base of the dome, rather than being designed for the artistic purposes for which they were often employed. The authors singled out properties like the necessary number of four and their specific three-dimensional shape.

read more »

February 12, 2013

Segmented Sleep

Segmented sleep, also known as divided sleep, bimodal sleep pattern, or interrupted sleep, is a polyphasic or biphasic sleep pattern where two or more periods of sleep are punctuated by a period of wakefulness. Along with a nap (siesta) in the day, it has been argued that this is the natural pattern of human sleep. A case has been made that maintaining such a sleep pattern may be important in regulating stress.

Historian A. Roger Ekirch argues that before the Industrial Revolution, segmented sleep was the dominant form of human slumber in Western civilization. He draws evidence from documents from the ancient, medieval, and modern world, which he discovered over the course of fifteen years of research. Other historians, such as Craig Koslofsky, have endorsed Ekirch’s discovery and analysis.

read more »