Sunday, June 26, 2005

ClockNews #32 - Infants, Adolescents, Doctors, Patients and Travellers

Cycled Light Promotes Growth in Pre-term Infants
A Duke University Medical Center study has shown that exposing babies born before 31 weeks of gestation to cycled light helps them grow faster, and the study identifies no short-term advantages to keeping infants in total near darkness, the standard practice with many infants.

Separating morning and evening in the circadian clock of mammals
A key question for circadian biologists concerns the way in which seasonal changes in day-length alter the behavior of circadian clocks over the course of the year. One idea for which evidence has accumulated is that circadian clocks contain coupled “morning” and “evening” oscillators that are separately synchronized to dawn and dusk.

Researchers discover stem cell 'guide' that may be key for targeting neural stem cell treatments
The protein, a small peptide called prokineticin 2 (PK2), was found to play a key regulatory role for the proper functional integration of these new neurons in the brain. A few years ago, PK2 was shown by the same research group to be an important regulator of circadian rhythms.

His numbers are in the ballpark
For years he's suffered from a sleep disorder that can turn his schedule upside down -- day becomes night, night becomes day. On several occasions, he had to cancel interviews because it was bedtime at 3 p.m. Van's response to his illness has been predictable: He's researched it intensively, and over time developed theories about the brain that he believes could earn him a Nobel Prize someday.

Early Function Of Specialized Neurons Marks 'First Light' In Retinal Maturation
The researchers found that, quite remarkably, the melanopsin-expressing ganglion cells are present in abundance and act as functional photoreceptors from the day of birth, when it has been widely assumed the mouse retina lacks photodetection. At the time of birth, a significant percentage of cells in the retinal ganglion-cell layer express melanopsin and respond to light.

Researchers Say Sleep Gene Related to Addiction
Not only does drug use disrupt sleep, but researchers say that a gene involved in regulate circadian rhythms could influence the addictive response to drugs like cocaine.

Shooting Down the Breakfast Club
There is an alternate—and perhaps more compelling—explanation for why breakfast-eaters do relatively well in school while breakfast-skippers may have a tough time: The skippers are also the ones whose bodies rebel against early-morning activity. Their circadian clocks are telling them that it's still nighttime, or they're plain exhausted and need the extra zzz's. Taken together, the scientific literature on breakfast and sleep suggests that making sure kids get enough shut-eye will probably do more for them than dragging them out of bed to eat their Wheaties.

Teenagers need help to form better sleep habits
Left to their own devices, teenagers sleep about nine hours a night, studies show. Generally, they go to bed later and wake up later than younger children and adults, perhaps due to hormonal-induced changes in circadian rhythm.

Exposure to daylight reduces hospital recuperation times
Building developers, architects, hospital and city planners, and interior designers take note: according to Dr. Asher Derman, building and design environmental consultant (Battery Park City, AOL-Time Warner), a small but important group of recent medical and health care related studies are beginning to link exposure to daylight and window views within buildings with decreases in recuperation times for hospitalized patients.

New Study Showed Ramelteon Helped Adults With Chronic Insomnia Fall Asleep, Sleep Longer
Ramelteon, a novel investigational compound under review with the FDA for the treatment of insomnia, reduced the time it took to fall asleep and increased total sleep time in adults with chronic insomnia, according to results from a Phase 3 study presented this week at the 19th Annual Meeting of the Associated Professional Sleep Societies (APSS). Results of the study also showed no evidence of rebound insomnia, next-day impairments or withdrawal effects due to discontinuation.

Sudden climate change is not just about Eskimos in bikinis
Take that marmot. The yellow-bellied marmot's hibernation habits are guided by ancient circadian rhythms that are cued by seasonal changes in light and temperature. Like their cousin Punxsutawney Phil, marmots awake from winter hibernation in underground burrows and surface when they sense the earth is warming. In recent years, conservationists report, marmots are emerging from their holes a month sooner than expected. But if the ground warms before deep snowpack melts, which is now often the case, emerging marmots cannot get to food and they starve.

Night and rotating shift workers sleepy
European workers who regularly work at night, and those who work rotating day and night shifts, are at high risk for excessive daytime sleepiness.

Fear and freedom when darkness fell -
Before electricity, night determined how we lived, loved and slept

Who knew that nighttime had a history? A. Roger Ekirch knows because for 20 years he has been working by artificial light in archives and libraries all over Europe to develop a picture of what it was like to live before gas, and then electricity, changed the nightscape into a mere extension of the worlds of work and play. "At Day's Close" provides a panorama of the night from the 16th through the 18th centuries, from Scandinavia to the Mediterranean, with an occasional foray into the North American colonies. Ekirch shows that in the early modern period, the rhythms of life were not what they are today and that Europeans of that period lived in two worlds: one ruled by light and the rules of society, and the other governed by anxiety, fantasy and a dreamy kind of community.
The final section of "At Night's Close" underscores how even the biological rhythms of sleep have changed since the advent of gas and electric lighting. People slept differently in the early modern period because their circadian patterns had not been altered by the persistence of light beyond sunset. Ekirch is fascinated by accounts of "a first sleep," after which people would lie awake for long stretches of time before returning to their slumbers. He speculates that this gave them more ready access to their dreams, and he goes on to make the surprising claim that such access means that early modern people had a greater capacity for psychological insight than we whose sleep cycle has been modified by artificial light. Although his explanation for our supposed diminished capacity for psychological revelation is at best unpersuasive, it does seem quite right to recognize how lighting may have altered the state of our biology as well as our society.

Beauty sleep helps to drive the mind
Research conducted at the Dial-a-Bed Sleep Laboratory at Wits University in Johannesburg shows why winter-time rising is so much harder than in summer.

People with Outgoing Personalities are More Likely to Underestimate How Sleepy They Really Are
How Sleepiness Relates to Personality and Work Schedules is Examined in Two Abstracts to be Presented at 19th Annual Meeting of the APSS

European Working Time Directive May Put Doctors' and Patients' Lives at Risk
Recent studies from the United States have proved the risks to patients and doctors of long working hours. Any shift system should have as few successive night shifts as possible, with a maximum of three consecutive nights. A single night shift, with a day off before and after, is reported to show the least distortion of circadian rhythms.

Pakrasi to head Energy Department grand challenge
Specifically, Pakrasi's project will focus on the amazing cyanobacterium Cyanothece, a one-celled marine organism, the only bacteria with a circadian rhythm, or biological clock. In particular, Cyanothece has the uncanny ability to fix oxygen through photosynthesis during the day while fixing nitrogen through the night.

Incredibly, even though the organism has a circadian rhythm, its cells grow and divide in 10-14 hours.

"This is a mystery in biology," Pakrasi said. "Why does an organism do this and yet have a circadian rhythm? It must be that it gains something. We intend to find out."

To unravel the mystery, Pakrasi and his collaborators will be growing Cyanothece cells in photobioreactors, testing cells every hour to try to understand its light cycle at different times of the day. With the combined diverse expertise of 14 different laboratories, the scientists and engineers will examine numerous biological aspects of the organism.

Balanced Life: Why the body clock goes haywire with jet lag
Researchers in a study published in Current Biology zero in on the SCN in rats. They found that the SCN actually comprises two sections, dorsal and ventral. Rats were exposed to gradually changing light and darkness over a period of seven days, until they were in constant darkness. They looked at changes in the brains and discovered that the two sections of the SCN actually adjusted to the shifts in light at radically different rates. The ventral part of the SCN—which is connected to the light-sensitive retina—adjusted very quickly to the change in light. The dorsal part took days to adjust. The signaling pattern between the two sections gets confused, which sends all sorts of mixed messages throughout the body.

Sleep Deprivation a Serious Problem
One of the causes of a bad nights sleep is the interruption of our body's natural rhythms caused by changing light levels in our sleeping environment. One of the worst offenders is the television. Many people lie in bed and watch TV until falling asleep leaving the TV to play all night.

Afternoon classes might help increase teens performance
Skimping on sleep resulted in poorer school performance. Students reported feeling better in afternoon classes, and all of them did better at school in the afternoon than in the morning.
The researchers tried exposing some of the students to bright light in the early morning. Those light treatments didn't change the students' sleep cycles or academic performance, compared with a placebo.

Lack of sleep can affect teen athletic performance

Studies about sleep and circadian rhythms may have applications that extend outside the scientific arena and into athletic performance in young people.
Considering the negative effect of insufficient sleep on performance, one Rhode Island-based sleep expert concluded that sports teams traveling west may have the upper hand when playing on their rivals' home turf early in the day.

The importance of light in healthcare environments
Architect Mies van der Rohe stated: “The history of architecture is the history of man’s struggle for light, the history of the window.” However, in the rush to create commercially-viable and technologically advanced healthcare institutions, the importance of appropriate lighting has been forgotten and the cost of employing people outnumbers the cost of operating a lighting system by approximately 150 to one.

At the same time, the effect of light on our physiological systems cannot be denied; the human circadian pacemaker is extremely sensitive to dim light, with a light intensity equivalent to indoor room light able to significantly shift the timing of the circadian system. While the long term effects of inappropriate light exposure are under investigation, misalignment between the internal circadian pacemaker and the external environment is thought to contribute to health problems such as cardiovascular disease, diabetes, sleep and gastro-intestinal disorders.

New research explains jet lag
Turns out that your brain's master circadian clock is actually twins. When you're time-shifted, as in a transoceanic flight, one twin zips ahead of the other, resulting in jet lag.
Now, a University of Virginia scientist working with Dutch colleagues has pinpointed the "mother" neurotransmitter that makes the twins resume walking together side by side, putting your body clock back on track.

Weekend lie-in is part of growing up
TEENAGERS have been given the best excuse for lying in bed for hours at the weekend - it is part of their in-born cycle, according to new research.
A US study published yesterday in the journal Paediatrics found that early school starts were forcing students to perform academically at a time of day when they were at their worst.
Don't blame Kevin: It's his hormones
Biological changes at puberty make it difficult for adolescents to get the nine to 10 hours of sleep their bodies require, making them moody, lethargic and less alert, according to research published yesterday.
Teenagers who refuse to emerge from beneath their duvets until after midday at weekends are neither lazy nor anti-social - they are repaying their accumulated "sleep debt".


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