Wednesday, November 6, 2013 at 08:54PM "We get more REM sleep in the last half of the night. Which means that if you are woken unexpectedly, your brain may not have dealt with all your emotions - which could leave you stressed and anxious. Drinking alcohol late at night is not a good idea as it reduces your REM sleep while it's being processed in your body."
Learn More: How much can an extra hour's sleep change you?
Saturday, July 9, 2011 at 08:53PM 
Blue light at night can lead to an unproductive day.By Dr. John
In 1893, Nikoli Tesla lit up the night at the Columbian Exposition in Chicago. His inventions in alternating electric current, together with Edison’s work on filaments, allowed us to end night at will. Now ubiquitous, artificial lighting disrupts sleep by inhibiting the production of melatonin, the light-sensitive hormone that induces sleep. As Laura Beil writes in New York Times:
Light hitting the retina suppresses the production of melatonin — and there lies the rub. In this modern world, our eyes are flooded with light well after dusk, contrary to our evolutionary programming. Scientists are just beginning to understand the potential health consequences. The disruption of circadian cycles may not just be shortchanging our sleep, they have found, but also contributing to a host of diseases.
In the computer age, we are taking the lighting revolution a step further; a step that may be giving us the Sleep Blues. While light of any wavelength can disrupt sleep, blue wavelengths, such as those emitted by the computer screen you are using, appear to be the most disruptive. Beil, quoting neurologist and sleep specialist Dr. George Brainard:
An LED screen bright enough and big enough “could be giving you an alert stimulus at a time that will frustrate your body’s ability to go to sleep later,” said Dr. Brainard. “When you turn it off, it doesn’t mean that instantly the alerting effects go away. There’s an underlying biology that’s stimulated.
Incandescent bulbs, which produce more red wavelengths, appear to inhibit melatonin production less than the blue wavelengths given off by LED monitors and energy-efficient bulbs. Thus, if you enjoy bedtime reading but are having a hard time going to sleep, an “old fashioned” bedside lamp and a print book may be your best choice.
Related Posts
The end of night
Paleolithic & hunter-gatherer sleep
Dim lights at dusk for better sleep
Changes in brain architecture due to altered sleep/wake cycles
Thursday, January 20, 2011 at 09:18PM Our physiology is linked to the planet through circadian rhythms. Specifically, our sleep/wake cycle is synched to the 24-hour light/dark cycle of the Earth. What happens to the brain when the light/dark cycle is shortened from 24-hours to 20-hours?
Researchers at Rockefeller University studied this in mice. Mice exposed to a 20-hour light/dark cycle gained weight and some became obese. More bothersome and surprising was the development of alterations in brain architecture: dendrites (the projections that transmit information from other nerve cells to the body of the neuron) became shorter and the organization of nerve cells “in the prelimbic prefrontal cortex, a brain region important in executive function and emotional control” became less complex. The author's conclusion:
How our findings translate to humans living and working in chronic circadian disruption is unknown, but we believe that this model can provide a foundation to understand how environmental disruption of circadian rhythms impacts the brain, behavior, and physiology.
What is not known is whether these changes correct themselves after the mice are returned to the endogenous 24-hour cycle. Possibly this will be the subject of a subsequent study.
Related Entries
Dim lights at dusk for better sleep
Paleolithic & hunter-gatherer sleep
The end of night
Sleep, sleep/wake cycles in Sleep Tuesday, January 18, 2011 at 08:39PM 
Sleep is fundamental to good health. Sleep impacts the quality of your day, and what happens during the day impacts the quality of your sleep. While many factors affect sleep, one we can control, yet often don’t, is the intensity of light we are exposed to before bedtime.
As we saw in The End of Night, the development of the light bulb and alternating current allowed us to effectively eliminate night at will. Since most of us prefer to get a good night's sleep, recall during the Paleolithic the slow decrease in light intensity at dusk prepared the brain for sleep, primarily by the secretion of melatonin. Today, we often keep the room lights on until bedtime and then, once turned off, expect to fall asleep effortlessly. For millions of Americans, the failure to adequately prepare the brain results in nonrestorative sleep.
According to EurekAlert, the Journal of Clinical Endocrinology & Metabolism will publish an article comparing normal room light versus dim light on the secretion of melatonin:
Thursday, December 2, 2010 at 08:28PM 
Poor sleep is a major barrier to good health. Before we consider ways to improve our sleep, we need to look back to the Paleolithic and to hunter-gatherer societies. Paleo-anatomists studying fossilized skeletons of Australopithecus and Homo habilis note they were well adapted to climbing. Although they probably spent much of daytime on the ground, they likely slept in trees. Sleeping on the ground probably began with the control of fire, which, in addition to improving nutrition, provided safety.
The first hominid to control fire may have been late Homo habilis, or Homo ergaster. Cooking provided a higher quality and more digestible diet, which led to a smaller gut and a larger brain (the expensive tissue hypothesis). Both day and night could be spent on the ground and hominid anatomy slowly became more human-like. The resulting hominid, Homo erectus, was tall and well adapted for migration over land. Their vestibular anatomy also indicates a primarily ground-based existence.
Richard Wrangham, Professor of Anthropology at Harvard, in his book Catching Fire: How Cooking Made Us Human, writes:
Monday, November 22, 2010 at 10:18PM 
Columbian Exposition in Chicago, 1893 - the dawn of the age of light. Image: PBS.orgOver 60 million Americans have problems sleeping. While insomnia has many causes, one is the use of electric lighting. Our circadian rhythms developed from the 24-hour rotation of the Earth. At the end of the day, the slowly fading sunlight allowed the brains of our hominid ancestors to prepare for sleep. Around 1 million years ago, hominids began to use fire and congregate around campfires for warmth and safety. Socialization increased. Eventually cooking developed and led to further brain evolution.
The first lamps, made from moss or other plant material and animal fat placed in a natural stone recesses, are tens of thousands of years old. Portable lamps fueled by animal fat, and later oil, were carried by Cro-Magnon into the deep recesses of the Lascaux and Altamira caves where they painted remarkable images of ice age fauna 13,000-18,000 years ago.
First used around 400 AD, candles were an important form of lighting for 1,500 years until the development of gas lighting at the end of the eighteenth century. As noted in A History of Light and Lighting, candles could be linked together to create a spectacle:
In 1761, at the coronation of George III, groups of 3000 candles were connected together with threads of gun cotton, and lit in half a minute. Those clustered below were showered with hot wax and burning thread.
Campfires, oil lamps, candles and gas lamps cast a dim light and
