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Seasonal variation in daylight influences brain function -- ScienceDaily

"In the study, we observed that the number of opioid receptors was dependent on the time of the year the brain was imaged. The changes were most prominent in the brain regions that control emotions and sociability. The changes in the opioid receptors caused by the variation in the amount of daylight could be an important factor in seasonal affective disorder," says Postdoctoral Researcher Lihua Sun from the Turku PET Centre and the University of Turku.

A sleep disorder associated with shift work may affect gene function: Going on holiday has a restorative effect on changes in DNA -- ScienceDaily

A total of 32 shift workers participated in the study, of whom 21 suffered from shift work disorder and 11 were in the control group. Dynamic changes to DNA methylation were investigated through a genome-wide analysis during work and after a holiday period. Changes to DNA methylation which affected gene function were identified in study subjects suffering from a sleep disorder caused by shift work. The findings demonstrated that rest and recovery during holiday periods also resulted in the restoration of DNA methylation in cases where changes had been observed during the work period. The study proved the dynamic nature of DNA methylation, which was particularly emphasised in the activity of NMDA glutamate receptors. The strongest evidence was gained from the GRIN2C receptor: the methylation level of a specific CpG base pair in the regulatory region was lower during the work period in subjects suffering from shift work disorder. However, this change was reversed after the holiday period.

Ancient echoes: Moonlight affects human sleep patterns | YaleNews

nt’s sleep duration across the lunar cycle ranged from 20 minutes to more than 90 minutes with little difference between the three indigenous groups, according to the study. Changes in the time that people fell asleep varied from a half hour to 80 minutes, the study found. The findings among the college students were consistent with these ranges. In all cases, people went to bed latest, and slept the least amount of time, three to five days before a full moon, according to the study. Interviews with Toba/Qom individuals indicated that moonlit nights are a particularly rich period for social activities, and elders reported that sufficient moonlight enables nighttime hunting and fishing, according to the study.

Study links exposure to nighttime artificial lights with elevated thyroid cancer risk -- ScienceDaily

Among 464,371 participants who were followed for an average of 12.8 years, 856 cases of thyroid cancer were diagnosed (384 in men and 472 in women). When compared with the lowest quintile of light at night, the highest quintile was associated with a 55 percent higher risk of developing thyroid cancer.

New study on circadian clock shows 'junk DNA' plays a key role in regulating rhythms -- ScienceDaily

With the help of Caitlyn Miller, a biochemistry undergraduate from USC Dornsife, researchers then verified the impact on circadian rhythms by inactivating certain miRNAs identified by the screen in their line of glowing cells. Knocking out the miRNAs had the opposite effect on the cells' circadian rhythm as adding them to the cells.

Effect of time of day of recreational and household physical activity on prostate and breast cancer risk (MCC‐Spain study) - Weitzer - - International Journal of Cancer - Wiley Online Library

We examined in a population‐based case‐control study (MCC‐Spain) if the time‐of‐day when physical activity is done affects prostate and breast cancer risk. Lifetime recreational and household physical activity was assessed by in‐person interviews. Information on time‐of‐day of activity (assessed approximately 3 years after the assessment of lifetime physical activity and confounders) was available for 781 breast cancer cases, 865 population female controls, 504 prostate cases and 645 population male controls from 10 Spanish regions, 2008‐2013. We estimated odds ratios (ORs) and 95% confidence intervals (95% CI) for different activity timings compared to inactive subjects using unconditional logistic regression adjusting for confounders. Early morning (8‐10 am) activity was associated with a protective effect compared to no physical activity for both breast (OR = 0.74, 95% CI = 0.48‐1.15) and prostate cancer (OR = 0.73, 95% CI = 0.44‐1.20); meta‐OR for the two cancers combined 0.74 (95%CI = 0.53‐1.02).

Internal clocks drive beta cell regeneration -- ScienceDaily

To explore the connection between internal biological clocks and beta cell regeneration, Charna Dibner's team first observed two groups of mice with only 20% beta cells remaining after targeted massive ablation. Mice in a first group were arrhythmic, whereas the control group had perfectly functional clocks. "The result was very clear: the mice bearing dysfunctional clocks were unable to regenerate their beta cells, and suffered from severe diabetes, while the control group animals had their beta cells regenerated; in just a few weeks, their diabetes was under control," says Volodymyr Petrenko, a researcher in Dr. Dibner's laboratory and the leading scientist in this study. By measuring the number of dividing beta cells across 24 hours, the scientists also noted that regeneration is significantly greater at night, when the mice are active.

60 minutes of endurance training is enough to shift body clock in mice -- ScienceDaily

This means that exercise is a cue for setting the clocks in muscles. The researchers determined this by studying mice that ran in different phases of the day: in the middle of their rest phase, an hour before starting their active phase, and in the middle of their active phase. Active and rest phases in mice are equivalent to day and night in humans. They then looked at how the amount of a primary clock protein changed over the course of multiple days following muscle contractions. Their results showed that depending on the timing of contractions the clocks shifted about an hour to either an earlier or later time and that this does not require circulating hormones or the central clock.

Disrupted circadian rhythms linked to later Parkinson's diagnoses: Researchers probe brain's 24-hour biological clock for neurodegenerative risks -- ScienceDaily

The scientists said their discovery of the link between circadian rhythms and Parkinson's -- a disease characterized by loss of control over movement, balance and other brain functions -- suggests these circadian disruptions may reflect neurodegenerative disease processes already affecting the brain's internal clock well before a Parkinson's diagnosis, and that they could be considered an early warning sign of the disease.

A role reversal for the function of certain circadian network neurons -- ScienceDaily

The researchers observed that fruit flies lacking dorsal termini were unable to properly synchronize their sleep/activity rhythms to daily temperature cycles. Previous research has shown that temperature changes play a role in regulating circadian rhythms. These new findings strongly suggest that dorsal medial termini neurons likely input (receive) signals from regions of the brain that track environmental temperature. "I have been curious for some time to know whether the structural plasticity that I characterized in clock neurons as a part of my graduate student work was an output mechanism for the clock to connect with downstream targets," said the study's first and co-senior author Maria Fernández, an assistant professor in the Department of Neuroscience and Behavior at Barnard College. "We were surprised to see that this site of plasticity seems to be involved in input, rather than output, pathways."

Gut reaction: How immunity ramps up against incoming threats -- ScienceDaily

Eating causes a hormone called VIP to kickstart the activity of immune cells in response to potentially incoming pathogens or 'bad' bacteria. The researchers also found that immunity increased at anticipated mealtimes indicating that maintaining regular eating patterns could be more important than previously thought. With the rise in conditions associated with chronic inflammation in the gut, such as irritable bowel and Crohn's disease, a better understanding of the early protective mechanisms governing gut health could help researchers to develop prevention strategies against unwanted inflammation and disease.

Learning from the bears -- ScienceDaily

A grizzly bear only knows three seasons during the year. Its time of activity starts between March and May. Around September the bear begins to eat large quantities of food. And sometime between November and January, it falls into hibernation. From a physiological point of view, this is the strangest time of all. The bear's metabolism and heart rate drop rapidly. It excretes neither urine nor feces. The amount of nitrogen in the blood increases drastically and the bear becomes resistant to the hormone insulin.

Before bed may be the best time to take blood pressure meds, study suggests | MinnPost

“The same medication ingested at different times of the day actually has different pharmacological properties, behaving like totally different medications,” explained Ramón Hermida, the study’s lead author and a chronobiologist at the University of Vigo in Spain, in an interview with NBC News.

Scientists discover skin keeps time independent of the brain -- ScienceDaily

But, he said, this study found that the skin actually expresses its own photoreceptors using a previously mysterious member of the opsin gene family, neuroposin. This means that skin can sense whether it is day or night even when it's cultured by itself in a dish. "If you simulate taking the cultured skin from Seattle to Japan (by simulating the light changes across time zones), the skin figures out that the time zone has changed and adapts to the new time zone within days because of neuropsin," said co-author Russ Van Gelder, professor and chair of ophthalmology at the UW School of Medicine. .

Chronobiology: Sleep and synaptic rhythms -- ScienceDaily

In the second study published in the same issue of Science the same group, in collaboration with a group from the University of Zürich (Steve Brown), has showed that synaptic protein abundance is also rhythmically shaped by sleep-wake cycles. In particular, they demonstrated that synaptic activity triggers the cycling production of proteins from messenger molecules that rhythmically accumulate at the synapses across the day. While protein production completely depends on wake-sleep cycles, messenger molecules travel and accumulate in the synapses predominantly in response to circadian mechanisms.

Molecule links weight gain to gut bacteria -- ScienceDaily

The study also found that microbes program these so-called circadian rhythms by activating a protein named histone deacetylase 3 (HDAC3), which is made by cells that line the gut. Those cells act as intermediaries between bacteria that aid in digestion of food and proteins that enable absorption of nutrients. The study, done in mice, revealed that HDAC3 turns on genes involved in the absorption of fat. They found that HDAC3 interacts with the biological clock machinery within the gut to refine the rhythmic ebb and flow of proteins that enhance absorption of fat. This regulation occurs in the daytime in humans, who eat during the day, and at night in mice, which eat at night. "The microbiome actually communicates with our metabolic machinery to make fat absorption more efficient. But when fat is overabundant, this communication can result in obesity. Whether the same thing is going on in other mammals, including humans, is the subject of future studies," added lead author Dr. Zheng Kuang, a postdoctoral fellow in the Hooper laboratory.

Biological clock influences immune response efficiency -- ScienceDaily

"Our study shows that T cells are more prone to be activated at certain times of the day. Identifying the mechanisms through which the biological clock modulates the T cell response will help us better understand the processes that regulate optimal T cell responses. This knowledge will contribute to improving vaccination strategies and cancer immune therapies," states Nathalie Labrecque, Professor at the Departments of Medicine and Microbiology, Infectious Diseases and Immunology at Université de Montréal.

Insulin under the influence of light -- ScienceDaily

To better assess the effect of light on tissue sensitivity to insulin, researchers measured insulin-induced glucose absorption. It turns out that a small disturbance in photic inputs (e.g. an hour of light exposure in the middle of the dark cycle, or light removal for 2 days) is enough to cause a negative effect. Indeed, increased or decreased light exposure can profoundly influence the sensitivity of tissues to insulin and the alteration, however minimal, of this mechanism is sufficient to significantly disrupt metabolic homeostasis. This would explain why people exposed to light at the wrong time -- workers in shift patterns, for example -- are more likely to develop metabolic diseases (e.g. diabetes).

Dead zones in circadian clocks -- ScienceDaily

One of the important properties of circadian clocks is the response to light signals, which enables organisms to become entrained to the 24-hour light-dark cycle on Earth. It has been shown that circadian clocks respond to light signals during the night, whereas they do not respond to such signals during the daytime. This holds true even when an organism is kept in complete darkness; a short light pulse does not change the time of the circadian clock when body time of the individual is at daytime. The time period in which the circadian clock is insensitive to light signals is referred to as the "dead zone." Previous studies have indicated that the presence of a dead zone improves the robustness of the clock. However, the mechanism underlying its generation is unclear.

How eating feeds into the body clock -- ScienceDaily

Dr Priya Crosby, a researcher at the MRC LMB and lead author on the study, highlighted: "Our data suggests that eating at the wrong times could have a major impact on our circadian rhythms. There is still work to do here, but paying particular attention to meal timing and light exposure is likely the best way to mitigate the adverse effects of shift-work. Even for those who work more traditional hours, being careful about when we eat is an important way to help maintain healthy body clocks, especially as we age."

Study links fluorescent lighting to inflammation and immune response - Neuroscience News

“In this report, we show genome-wide changes of gene expression patterns in skin, brain and liver for two commonly utilized fish experimental models (zebrafish and Japanese rice fish, also known as medaka), and a mammalian (mice), following exposure to 4,100 K ‘cool-white’ fluorescent light,” Walter said. “In spite of the extreme divergence of these animals (i.e., estimated divergence of mice and fish about 450 million years), and drastically different lifestyles (i.e., diurnal fish and nocturnal mice), the same highly conserved primary genetic response that involves activation of inflammation and immune pathways as part of an overall acute phase response was observed in the skin, brain and liver of all three animals. Follow-up studies to further define this response in mice are underway.”

Morning exercise for optimal metabolic impact

They found that a protein called hypoxia-inducible factor 1-alpha (HIF-1α) plays an important role and that it is activated by exercise in different ways depending on the time of day. HIF-1α is a transcription factor that is known to stimulate certain genes based on oxygen levels in tissue. “It makes sense that HIF-1α would be important here, but until now we didn’t know that its levels fluctuate based on the time of day,” Sassone-Corsi says. “This is a new finding.” Based on the work from the UC Irvine team, exercise seemed to have the most beneficial impact on the metabolism at the beginning of the active phase phase (equivalent to late morning in humans) compared with the resting phase (evening).

Two studies explore whether time of day can affect the body's response to exercise - Neuroscience News

The researchers also studied 12 humans and found similar effects. Overall, the people in the study had lower oxygen consumption while exercising in the evening compared with the morning; this translated to better exercise efficiency.

Fat cells work different 'shifts' throughout the day -- ScienceDaily

During this unique study seven participants underwent regulated sleep-wake cycles and meal times before entering the laboratory, where they maintained this routine for a further three days. Participants then experienced a 37- hour 'constant routine' during which time they did not experience daily changes in light-dark, feed-fast and sleep-wake cycles. Biopsies of fat tissue were taken at six hourly intervals and then followed by an analysis of gene expression. Researchers identified 727 genes in the fat tissue that express their own circadian rhythm, many carrying out key metabolic functions. A clear separation in gene rhythms was identified with approximately a third peaking in the morning and two thirds in the evening.

Exercise in Morning or Afternoon to Shift Your Body Clock Forward – Neuroscience News

This study found that exercising at 7 am or between 1 and 4 pm advanced the body clock to an earlier time, and exercising between 7 and10 pm delayed the body clock to a later time. Exercising between 1 and 4 am and at 10 am, however, had little effect on the body clock, and the phase-shifting effects of exercise did not differ based on age nor gender.

Disrupted circadian rhythms may drive anxiety and exacerbate brain disorders

"The studies presented today help deepen our understanding of why sleep is disrupted in so many patients," said press conference moderator Clifford Saper, MD, Ph.D., of Harvard Medical School, who's work focuses on integrated functions maintained by hypothalamus which includes the regulation of wake-sleep cycles. "They also suggest that sleep-focused therapies, such as treatments to regulate circadian rhythms, may be beneficial in the prevention or treatment of a vast array of diseases, including Alzheimer's disease and anxiety disorder and furthermore emphasize the critical need of good sleep for everyone's health."