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'Nested sequences': An indispensable mechanism for forming memories -- ScienceDaily

Which of these sequences, slow or nested, is necessary for the appearance of sequence reactivations, and therefore causes the consolidation of memories during sleep? Using an ingenious system, the researchers discovered what deactivates nested sequences, without affecting slow sequences: the animals are transported on an electric train, in a car with a treadmill (see image). When the treadmill is stopped, the nested sequences disappear; they return when the treadmill starts again. The researchers then observed that after several circuits in the train with the treadmill stopped, place cells in the rats' hippocampi did not reactivate during sleep in the same order as when awake. On the contrary, after one train circuit with the treadmill on, the sequence reactivations are indeed present. So it is these nested theta sequences during movement that are indispensable for the consolidation of memory during sleep.

It's not just for kids -- even adults appear to benefit from a regular bedtime: Adults with varied sleep-wake times weigh more, have higher blood sugar, risk of disease -- ScienceDaily

Of all three measures, however, regularity was the best at predicting someone's heart and metabolic disease risk, the researchers found. As one might expect, irregular sleepers experienced more sleepiness during the day and were less active -- perhaps because they were tired, Lunsford-Avery said. Researchers plan to conduct more studies over longer periods in hopes of determining how biology causes changes in sleep regularity and vice-versa. "Perhaps there's something about obesity that disrupts sleep regularity," Lunsford-Avery said. "Or, as some research suggests, perhaps poor sleep interferes with the body's metabolism which can lead to weight gain, and it's a vicious cycle. With more research, we hope to understand what's going on biologically, and perhaps then we could say what's coming first or which is the chicken and which is the egg."

Brain connectivity study helps explain the neural link between depression and poor sleep quality

The researchers examined data from 1,017 participants who were included in the March 2017 public data release from the Human Connectome Project. They found that both poor sleep quality and depressive symptoms were associated with neural connectivities involving the lateral orbitofrontal cortex, the dorsolateral prefrontal cortex, the cingulate cortex, and the precuneus. “Our analysis shows that the functional connections between the areas of the brain associated with short-term memory, the self, and negative emotions are increased in both poor sleep and depressive participants. So people with poor sleep or depression may focus too much on the negative things and dwell on bad thoughts, which leads to a poor quality of sleep,” Feng told PsyPost.

Poor sleep triggers viral loneliness and social rejection: Lack of sleep generates social anxiety that infects those around us -- ScienceDaily

Notably, researchers found that brain scans of sleep-deprived people as they viewed video clips of strangers walking toward them showed powerful social repulsion activity in neural networks that are typically activated when humans feel their personal space is being invaded. Sleep loss also blunted activity in brain regions that normally encourage social engagement. "The less sleep you get, the less you want to socially interact. In turn, other people perceive you as more socially repulsive, further increasing the grave social-isolation impact of sleep loss," Walker added. "That vicious cycle may be a significant contributing factor to the public health crisis that is loneliness." National surveys suggest that nearly half of Americans report feeling lonely or left out. Furthermore, loneliness has been found to increase one's risk of mortality by more than 45 percent -- double the mortality risk associated with obesity.

Sensitivity of the circadian system to evening bright light in preschool‐age children

We found robust melatonin suppression (87.6 ± 10.0%) in response to the bright light stimulus. Melatonin levels remained attenuated for 50‐min after termination of the light stimulus (P < 0.008). Furthermore, melatonin levels did not return to 50% of those observed in the dim light condition 50‐min after the light exposure for 7/10 children.

How a single binge drinking episode affects gene that regulates sleep: Discovery explains alcohol's link to brain activity, sleep disturbances -- ScienceDaily

Using a mouse model, Thakkar monitored the effect of binge drinking on sleep patterns. Thakkar found mice exposed to binge drinking experienced a significant increase in non-rapid eye movement sleep four hours post-binge, followed by increased wakefulness and reduced sleep during subsequent sleep periods. Thakkar also discovered post-binge mice did not experience an increase in a sleep promoting chemical, adenosine, in the brain nor increased sleep pressure during sleep deprivation. The research also revealed binge alcohol consumption affects the gene that regulates sleep, resulting in sleep disturbances. "What we have shown in this research is that a particular gene -- which is very important for sleep homeostasis -- is altered by just one session of binge drinking," Thakkar said. "We were not expecting this. We thought it would be affected after multiple sessions of binge drinking, not one. That tells you that as soon as you consume four drinks, it can alter your genes."

Early birds less prone to depression: Largest study yet links chronotype to mental health -- ScienceDaily

In 2009, all the participants included in the study were free of depression. When asked about their sleep patterns, 37 percent described themselves as early types, 53 percent described themselves as intermediate types, and 10 percent described themselves as evening types. The women were followed for four years to see who developed depression. Depression risk factors like body weight, physical activity, chronic disease, sleep duration, or night shift work were also assessed. The researchers found that late chronotypes, or night owls, are less likely to be married, more likely to live alone and be smokers, and more likely to have erratic sleep patterns. After accounting for these factors, they found that early risers still had a 12 -- 27 percent lower risk of being depressed than intermediate types. Late types had a 6 percent higher risk than intermediate types ( this modest increase was not statistically significant.) "This tells us that there might be an effect of chronotype on depression risk that is not driven by environmental and lifestyle factors," said Vetter.

A bad night's sleep linked to suicidal thoughts the following day in people with depression

The researchers found that short sleep duration and poor sleep quality both predicted higher severity of suicidal ideation on the following day, even after controlling for anxiety and depression symptom severity. “However, suicidal thoughts did not predict sleep problems the following night,” Littlewood noted.

Napping and teenage learning

Routine nappers, who napped five to seven days in a week, had sustained attention, better nonverbal reasoning ability and spatial memory. How long to nap is also an important question? The sweet spot is between 30 to 60 minutes. A nap longer than one hour interferes with circadian rhythm. Participants who slept between 30 to 60 minutes produced better accuracy in attention tasks as well as faster speed. She recommends not to nap after 4 p.m., nor over-nap. Researchers were surprised to find a positive relationship between midday napping and nighttime sleep, which is different than the literature. Habitual nappers (who napped more often) tended to have a better nighttime sleep. “That’s different than the findings in the United States, where napping may serve as a function to replace sleep lost from the previous night. Consequently, that may interfere with the following night’s sleep,” Ji said. “In China, a midday nap is considered a healthy lifestyle. Routine nappers are more likely to experience healthy nighttime sleep. So routine nappers are essentially trained to sleep well and sleep more at night.”

Morning sun 99.9% correlates with improved sleep

The Pittsburgh Sleep Quality Index, the Demographic Data Form, and the Follow-up Form for Elderly were used for data collection, whereas the Pittsburgh Sleep Quality Index was used for sample selection. It was found that exposure to direct sunlight between 8 AM and 10 AM for 5 days seems to be effective in increasing the global sleep quality score (P < .001).

How REM and non-REM sleep may work together to help us solve problems -- ScienceDaily

Suppose I give you a creativity puzzle where you have all the information you need to solve it, but you can't, because you're stuck," says first author Penny Lewis, a professor at the Cardiff University School of Psychology. "You could think of that as you've got all the memories that you need already, but you need to restructure them -- make links between memories that you weren't linking, integrate things that you weren't integrating." Studies show that this kind of restructuring often happens while we are asleep, so Lewis and her co-authors drew on that literature, as well as physiological and behavioral data, to create a model of what might be happening during each stage. Their model proposes that non-REM sleep helps us organize information into useful categories, whereas REM helps us see beyond those categories to discover unexpected connections.

New findings explain how melatonin promotes sleep: Discovery may lead to new therapy for insomnia -- ScienceDaily

The experiments singled out one receptor, MT1, as the mechanism via which melatonin acts to inhibit the specific orexin neurons that wake you up. This discovery could help lead to medications that target only the MT1 receptor instead of multiple receptors, which could lead to fewer side effects for those who take sleep-promoting drugs. "Melatonin has been used as a sleep drug for many years, but people didn't know how it worked," Thakkar said. "Our research suggests that if you target the melatonin MT1 receptor, you will get the most sleep with minimal side effects."

The Science of Sleep: Dreaming, Depression, and How REM Sleep Regulates Negative Emotions – Brain Pickings

The more severe the depression, the earlier the first REM begins. Sometimes it starts as early as 45 minutes into sleep. That means these sleepers’ first cycle of NREM sleep amounts to about half the usual length of time. This early REM displaces the initial deep sleep, which is not fully recovered later in the night. This displacement of the first deep sleep is accompanied by an absence of the usual large outflow of growth hormone. The timing of the greatest release of human growth hormone (HGH) is in the first deep sleep cycle. The depressed have very little SWS [slow-wave sleep, Stages 3 and 4 of the sleep cycle] and no big pulse of HGH; and in addition to growth, HGH is related to physical repair. If we do not get enough deep sleep, our bodies take longer to heal and grow. The absence of the large spurt of HGH during the first deep sleep continues in many depressed patients even when they are no longer depressed (in remission). The first REM sleep period not only begins too early in the night in people who are clinically depressed, it is also often abnormally long. Instead of the usual 10 minutes or so, this REM may last twice that. The eye movements too are abnormal — either too sparse or too dense. In fact, they are sometimes so frequent that they are called eye movement storms.

Total sleep deprivation increases extracellular serotonin in the rat hippocampus. - PubMed - NCBI

Sleep deprivation exerts antidepressant effects after only one night of deprivation, demonstrating that a rapid antidepressant response is possible. In this report we tested the hypothesis that total sleep deprivation induces an increase in extracellular serotonin (5-HT) levels in the hippocampus, a structure that has been proposed repeatedly to play a role in the pathophysiology of depression. Sleep deprivation was performed using the disk-over-water method. Extracellular levels of 5-HT were determined in 3 h periods with microdialysis and measured by high performance liquid chromatography coupled with electrochemical detection. Sleep deprivation induced an increase in 5-HT levels during the sleep deprivation day. During an additional sleep recovery day, 5-HT remained elevated even though rats displayed normal amounts of sleep. Stimulus control rats, which had been allowed to sleep, did not experience a significant increased in 5-HT levels, though they were exposed to a stressful situation similar to slee-deprived rats. These results are consistent with a role of 5-HT in the antidepressant effects of sleep deprivation.

One Sleepless Night Increases Dopamine in the Human Brain

“This is the first time that a study provides evidence that in the human brain, dopamine is involved in the adaptations that result from sleep deprivation,” said Nora Volkow, MD, director of the National Institute on Drug Abuse, who led the study. Volkow and colleagues found that in healthy participants, sleep deprivation increased dopamine in two brain structures: the striatum, which is involved in motivation and reward, and the thalamus, which is involved in alertness. The researchers also found that the amount of dopamine in the brain correlated with feelings of fatigue and impaired performance on cognitive tasks. “These findings suggest dopamine may increase after sleep deprivation as a compensatory response to the effects of increased sleep drive in the brain,” said David Dinges, PhD, at the University of Pennsylvania School of Medicine, an expert unaffiliated with the study. “The extent to which this occurs may differentiate how vulnerable people are to the neurobehavioral effects of sleep loss,” Dinges said.

The link between circadian rhythms and aging: Gene associated with longevity also regulates the body's circadian clock -- ScienceDaily

Last year, Guarente found that a robust circadian period correlated with longer lifespan in mice. That got him wondering what role SIRT1, which has been shown to prolong lifespan in many animals, might play in that phenomenon. SIRT1, which Guarente first linked with aging more than 15 years ago, is a master regulator of cell responses to stress, coordinating a variety of hormone networks, proteins and genes to help keep cells alive and healthy.

Visualizing assemblies of the proteins that direct cyanobacterial circadian rhythms

KaiB, though, flips between two different shapes, and is only active when it's in an unstable shape—a situation that until now made crystallization impossible. "We mutated KaiB so that it stayed in its active shape, and when we added KaiA and KaiC they arranged themselves around it as they do at night," LiWang said. "We found the secret sauce that allows us to figure out how the springs and gears go together." They were amazed that they obtained crystals within a day of combining the proteins. They also solved an NMR structure of a complex between the active form of KaiB and the domain of a protein (CikA) that transmits signals to regulate gene expression in cyanobacteria. "It's really remarkable that the cyanobacterial clock is so dependent on this rare state of KaiB," Partch said. "The mechanistic information we're getting out of these structures is allowing us to piece together how the clock manages to keep 24-hour time. We're now looking for similar clues in other circadian timekeeping systems, including our own."

Sleep Shrinks the Brain--and That's a Good Thing - Scientific American

Cirelli said that one interesting finding was that this pruning occurred in about 80 percent of the synapses but spared the largest ones. These larger synapses may be associated with the most stable and important memories, connections the brain does not want to lose, the researchers speculated. Yet, the way in which the brain decides what synaptic connections to prune is another mystery to explore, Cirelli said. "It is critical to have pruning back at night, so that the huge amount of information encoded by temporary synapses during the day won't overwhelm the brain," said Foster. "Pruning ensures that only the most important information is retained."

Insomnia and depression: Japanese hospital workers questionnaire survey : Open Medicine

Chronic insomnia is the one of the factors influencing the development of mental illness. In this survey, we tried to clarify the relationship between chronic insomnia and various factors. Although there is no certainty about other possible independent variables, multiple regression analyses suggested that chronic insomnia is an important factor for depression. Koyama et al. found that subjects who suffered from severe sleeping disorders, not just during depression, tended to have decreased blood flow in the frontal lobe of the brain [2]. When SIGH-D was used to evaluate sleeping disorders, an IS of 3 or higher showed that its severity and the reduced blood flow in the frontal lobe are significantly correlated. Based on this biological finding, preliminary research was conducted with 108 working participants, which included healthy participants and patients with mild to moderate depressive episodes. The result showed that the IS was significantly correlated with the severity of depression, subjective fatigue, sadness, and suicidal thoughts. Thus, an IS evaluation has the possibility of identifying depression based on a questionnaire survey related to direct mood changes [3]. There have been robust findings concerning the biology underlying the close relationship between sleep disorders and depression. For example, Buckley has found that a protracted sleep disorder, not depression, induces hyperactivity of the HPA (hypothalamic-pituitary-adrenal axis) system [14]. Furthermore, exposure to extreme stress causes the excessive secretion of corticotropin releasing hormone (CRH) —a cerebral mechanism for stress adaptation. This release of CRH inhibits the activities of the serotonin pathway in the nervous system that extends from the dorsal raphe nucleus to the prefrontal area via the gamma-aminobutyric acid (GABA) system [15]. It is also known that CRH has a stimulant effect [14]. Therefore, it is inferred that a substantive lack of sleep will lead to a sustained activation of the HPA system once again, thus establishing a vicious cycle. On the other hand, the decline in frontal lobe function due to depression has been established by several earlier studies, including those that used functional brain imaging [15,16,17,18]. The protraction of a sleep disorder activating the HPA system and inhibiting the serotonin nervous system in the frontal lobe is believed to elicit a clinical condition similar to depression. Furthermore, the finding that the hyperactivity of the HPA system increases cortisol secretion, which inhibits the HPA system and damages hippocampal cells, further strengthens the suggested relationship between sleep disorders and depression. This biological finding strengthens the theory that a lack of sleep due to insomnia, exposure to stress, and overwork, leads to depression because of the accumulation of mental fatigue.

Amid ADHD spike, doctors urge closer look at sleep issues -- ScienceDaily

D-diagnosed children whose behavior only improves after better sleep quality and duration. Occasionally, he has found that ADHD medications are the root of the sleep issues.

irregular sleep screws you

the researchers were able to assess the timing of circadian rhythms. On average, melatonin was released 2.6 hours later in students with the most irregular sleep patterns, compared with students with more regular sleep patterns.

Amber-tinted glasses may provide relief for insomnia -- ScienceDaily

To test their theory, the researchers recruited 14 individuals with an insomnia diagnosis to take part in a small study. For seven consecutive nights, participants wore wrap-around frames with amber-tinted lenses that blocked blue light or with clear placebo lenses for two hours before bedtime. Four weeks later, participants repeated the protocol with the other set of glasses. The researchers found that participants got around 30 minutes extra sleep when they wore the amber lenses compared to the clear lenses. In self-reported sleep surveys, participants also reported greater duration, quality, and soundness of sleep, and an overall reduction in insomnia severity.

Antidepressants and the Placebo Effect

Yet this 11% figure may overestimate the number of people who benefit from antidepressants. Antidepressants are also prescribed to people who do not qualify for the diagnosis of major depression. My neighbor’s pet dog died; his physician prescribed an antidepressant. A friend in the US was diagnosed with lumbar muscle spasms and was prescribed an antidepressant. I have lost count of the number of people who have told me they were prescribed antidepressants when complaining of insomnia – even though insomnia is a frequently reported side effect of antidepressants. About 20% of patients suffering from insomnia in the United States are given antidepressants as a treatment by their primary care physicians (Simon & VonKorff, 1997), despite the fact that “the popularity of antidepressants in the treatment of insomnia is not supported by a large amount of convincing data, but rather by opinions and beliefs of the prescribing physicians” (Wiegand, 2008, p. 2411).

New insights into how sleep helps the brain to reorganize itself -- ScienceDaily

Dr Julie Seibt, Lecturer in Sleep and Plasticity at the University of Surrey and lead author of the study, said: "Our brains are amazing and fascinating organs -- they have the ability to change and adapt based on our experiences. It is becoming increasingly clear that sleep plays an important role in these adaptive changes. Our study tells us that a large proportion of these changes may occur during very short and repetitive brain waves called spindles. "Sleep spindles have been associated with memory formation in humans for quite some time but nobody knew what they were actually doing in the brain. Now we know that during spindles, specific pathways are activated in dendrites, maybe allowing our memories to be reinforced during sleep. "In the near future, techniques that allow brain stimulation, such as transcranial magnetic stimulation (TMS), could be used to stimulate dendrites with the same frequency range as spindles. This could lead to enhance cognitive functions in patients with learning and memory disorders, such as dementia."

Lack of sleep could contribute to mental health problems, researchers reveal | Society | The Guardian

After taking into account effects not linked to treatment – as deduced from the no-treatment group – insomnia in the CBT group was found to have fallen by almost half 10 weeks into the study, while both anxiety and depression dropped by a fifth, and paranoia and hallucinations fell by 25% and 30% respectively. “Having insomnia doubles your chances of developing depression and we now know that if you treat the insomnia it reduces depression,” said Freeman.

Is ADHD really a sleep problem? -- ScienceDaily

"There is extensive research showing that people with ADHD also tend to exhibit sleep problems. What we are doing here is taking this association to the next logical step: pulling all the work together leads us to say that, based on existing evidence, it looks very much like ADHD and circadian problems are intertwined in the majority of patients. We believe this because the day and night rhythm is disturbed, the timing of several physical processes is disturbed, not only of sleep, but also of temperature, movement patterns, timing of meals, and so on. If you review the evidence, it looks more and more like ADHD and sleeplessness are 2 sides of the same physiological and mental coin."