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Posts Tagged ‘sleep

Meaning Of Sleep Quality Subjective

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Both insomnia patients and normal sleepers define sleep quality by tiredness upon waking and throughout the day, feeling rested and restored upon waking, and the number of awakenings they experienced in the night. Further, people with insomnia have more requirements for judging sleep to be of good quality, according to a new study.

https://i2.wp.com/www.sciam.com/media/externalnews/2008-02-28T182441Z_01_NOOTR_RTRIDSP_2_HEALTH-SLEEP-USA-DC.jpg

“Good sleep quality is associated with a wide range of positive outcomes such as better health, less daytime sleepiness, greater well-being and better psychological functioning,” said Allison G. Harvey, PhD, of the University of California at Berkeley, lead author of the study. “Moreover, poor sleep quality is one of the defining features of chronic insomnia.”

So it is surprising that there is minimal systematic research devoted to how humans arrive at their subjective sense of whether they had a good or poor nights sleep. In this study, we used a range of methods to compare the sleep quality judgments of insomnia patients and good sleepers.

Two important findings were:

  1. Tiredness upon waking and throughout the day were most consistently associated with sleep quality judgments – this finding emphasizes the importance of the recent shift in the field to study daytime variables,
  2. Individuals with insomnia appear to have more requirements to be met before they feel have experienced a night of good sleep quality.

The study focused on 25 individuals with insomnia and 28 normal sleepers, whose descriptions of good and poor sleep quality nights were analyzed and recorded.

Insomnia is a classification of sleep disorders in which a person has trouble falling asleep, staying asleep or waking up too early. These disorders may also be defined by an overall poor quality of sleep. Insomnia is the most commonly reported sleep disorder. About 30 percent of adults have symptoms of insomnia.

Sleep Volume 31 / Issue 3 / March 1, 2008

The Subjective Meaning of Sleep Quality: A Comparison of Individuals with and without Insomnia 

Allison G. Harvey, PhD1; Kathleen Stinson, BA2; Katriina L. Whitaker, BSc2; Damian Moskovitz, BA1; Harvinder Virk, BA


1Department of Psychology, University of California, Berkeley, CA; 2Department of Psychiatry, University of Oxford, UK

Study objectives:

“Sleep quality” is poorly defined yet ubiquitously used by researchers, clinicians and patients. While poor sleep quality is a key feature of insomnia, there are few empirical investigations of sleep quality in insomnia patients. Accordingly, our aim was to investigate the subjective meaning of sleep quality among individuals with insomnia and normal sleepers.

Design:

Cross sectional between groups (insomnia vs. good sleeper). Analyses were conducted across three outcome variables: (1) a “Speak Freely” procedure in which participants’ descriptions of good and poor sleep quality nights were analysed, (2) a “Sleep Quality Interview” in which participants judged the relative importance of variables included in previous research on sleep quality and (3) a sleep quality diary completed over seven consecutive nights.

Setting:

University Department of Psychiatry

Participants:

Individuals with insomnia (n = 25) and normal sleepers (n = 28).

Interventions: N/A

Results:

Both the insomnia and normal sleeper groups defined sleep quality by tiredness on waking and throughout the day, feeling rested and restored on waking, and the number of awakenings they experienced in the night. The insomnia group had more requirements for judging sleep to be of good quality.

Conclusion:

The meaning of sleep quality among individuals with insomnia and normal sleepers was broadly similar. A comprehensive assessment of a patient’s appraisal of their sleep quality may require an assessment of waking and daytime variables.

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Written by huehueteotl

March 3, 2008 at 4:29 pm

Posted in Psychology

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‘Satiety Center’ Of The Mouse Brain

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By pitting two forces — hunger and circadian rhythms — against each other, researchers at Rockefeller University have identified the region of the mouse brain that first registers changes in food availability. The research, as aforesaid in mice, suggests that shifting the timing of a meal increases mental alertness even during times when they are usually at rest, findings that, perhaps, may have implications for targeting health concerns such as obesity and diabetes as well as optimizing performance on tasks that require sustained vigilance in humans.

To pit the need for food against the need for sleep, scientists led by Donald Pfaff, head of the Laboratory of Neurobiology and Behavior, gradually shifted the mice’s mealtime during the night, when mice are most active, to a four-hour window during the day, when they are usually at rest. Three days after the mealtime shift, the mice began to show classic signs of anticipatory behavior: wheel-running an hour or two before the timed meal. Compared to control animals, the shifted mice ran three times the distance on the wheel — increased activity signaling a heightened sense of alertness. This behavior also suggests that the light-dark cycle no longer regulated the mice’s behavioral arousal; food did.

The researchers used immunocytochemistry to test where in the brain these two arousal pathways converge. Out of the 16 brain regions tested, only one had become activated: the ventromedial hypothalamus, a group of neurons known as the satiety center of the brain. Animals, including humans, tend to stop eating when this region is activated, and damage to this group of neurons leads to obesity. The activity of the paraventricular nucleus, a region that produces many hormones, was decreased.

“Since we examined the brain as close as possible to the development of this anticipatory behavior,” says postdoc Ana Ribeiro, “the neuronal changes we observed are the ones most likely causing the changes in behavioral arousal. These regions are thus the best targets for modulating arousal.”

As about implications for humans, first author Ribeiro daringly claims that to optimize performance on tasks that require sustained vigilance, ones performed by air-traffic controllers, physicians, the military and others, understanding the neural mechanisms and molecules involved in mediating arousal becomes important. “This research,” she says, “gives us a big clue as to what these mechanisms may be.”

PNAS | December 11, 2007 | vol. 104 | no. 50 | 20078-20083
Two forces for arousal: Pitting hunger versus circadian influences and identifying neurons responsible for changes in behavioral arousal
Ana C. Ribeiro*,{dagger}, Evelyn Sawa*, Isabelle Carren-LeSauter*, Joseph LeSauter{ddagger}, Rae Silver{ddagger},§, and Donald W. Pfaff*,{dagger}

*Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10021; {ddagger}Department of Psychology, Barnard College, New York, NY 10027; §Department of Psychology, Columbia University, New York, NY 10027; and Department of Anatomy and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY 10032

Contributed by Donald W. Pfaff, October 24, 2007 (received for review July 6, 2007)

The mechanisms underlying CNS arousal in response to homeostatic pressures are not known. In this study, we pitted two forces for CNS arousal against each other (circadian influences vs. restricted food availability) and measured the neuronal activation that occurs in a behaviorally defined group of animals that exhibited increased arousal in anticipation of feeding restricted to their normal sleeping time. The number of c-FOS+ neurons was significantly increased only in the ventromedial nucleus of the hypothalamus (VMH) in these mice, compared with control animals whose feeding was restricted to their normal active and feeding time (P < 0.01). Because the activation of VMH neurons coincides with the earliest signs of behavioral arousal preceding a change in meal time, we infer that VMH activation is involved in the increased arousal in anticipation of food.

Written by huehueteotl

January 29, 2008 at 9:54 am

Brain Stronger During Waking Hours, Weaker During Sleep

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Most people know it from experience: After so many hours of being awake, your brain feels unable to absorb any more–and several hours of sleep will refresh it.

Now new research clarifies this phenomenon, supporting the idea that sleep plays a critical role in brain’s ability to change in response to its environment. This ability, called plasticity, is at the heart of learning.

The UW-Madison scientists showed by several measures that synapses — nerve cell connections central to brain plasticity — were very strong when mice had been awake and weak when they had been asleep.

The new findings reinforce the UW-Madison researchers’ highly-debated hypothesis about the role of sleep. They believe that people sleep so that their synapses can downsize and prepare for a new day and the next round of learning and synaptic strengthening.

The human brain expends up to 80 percent of its energy on synaptic activity, constantly adding and strengthening connections in response to all kinds of stimulation, explains study author Chiara Cirelli, associate professor of psychiatry.

Given that each of the millions of neurons in the human brain contains thousands of synapses, this energy expenditure “is huge and can’t be sustained.”

“We need an off-line period, when we are not exposed to the environment, to take synapses down,” Cirelli say. “We believe that’s why humans and all living organisms sleep. Without sleep, the brain reaches a saturation point that taxes its energy budget, its store of supplies and its ability to learn further.”

To test the theory, researchers conducted both molecular and electro-physiological studies in rats to evaluate synaptic potentiation, or strengthening, and depression, or weakening, following sleeping and waking times. In one set of experiments, they looked at brain slices to measure the number of specific receptors, or binding sites, that had moved to synapses.

“Recent research has shown that as synaptic activity increases, more of these glutamatergic receptors enter the synapse and make it bigger and stronger,” explains Cirelli.

The Wisconsin group was surprised to find that rats had an almost 50 percent receptor increase after a period of wakefulness compared to rats that had been asleep.

In a second molecular experiment, the scientists examined how many of the receptors underwent phosphorylation, another indicator of synaptic potentiation. They found phosphorylation levels were much higher during waking than sleeping. The results were the same when they measured other enzymes that are typically active during synaptic potentiation.

To strengthen their case, Cirelli and colleagues also performed studies in live rats to evaluate electrical signals reflecting synaptic changes at different times. This involved stimulating one side of each rat’s brain with an electrode following waking and sleeping and then measuring the “evoked response,” which is similar to an EEG, on another side.

The studies again showed that, for the same levels of stimulation, responses were stronger following a long period of waking and weaker after sleep, suggesting that synapses must have grown stronger.

“Taken together, these molecular and electro-physiological measures fit nicely with the idea that our brain circuits get progressively stronger during wakefulness and that sleep helps to recalibrate them to a sustainable baseline,” says Cirelli.

The theory she and collaborator Dr. Giulio Tononi, professor of psychiatry, have developed, called the synaptic homeostasis hypothesis, runs against the grain of what many scientists currently think about how sleep affects learning. The most popular notion these days, says Cirelli, is that during sleep synapses are hard at work replaying the information acquired during the previous waking hours, consolidating that information by becoming even stronger.

“That’s different from what we think,” she says. “We believe that learning occurs only when we are awake, and sleep’s main function is to keep our brains and all its synapses lean and efficient.”

Brain Research Bulletin

doi:10.1016/j.brainresbull.2007.10.040 

Research report

Cortical metabolic rates as measured by 2-deoxyglucose-uptake are increased after waking and decreased after sleep in mice

V.V. Vyazovskiya, b, C. Cirellinext termb, G. Tononib, Corresponding Author Contact Information, E-mail The Corresponding Author and I. Toblera, Corresponding Author Contact Information, E-mail The Corresponding Author
aInstitute of Pharmacology and Toxicology, University of Zurich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland
bDepartment of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Boulevard, Madison, WI 53719, USA
Received 10 August 2007;  revised 11 October 2007;  accepted 12 October 2007.  Available online 20 November 2007.

Abstract

A recent hypothesis suggests that a major function of sleep is to renormalize previous termsynapticnext term changes that occur during wakefulness as a result of learning processes [G. Tononi, C. Cirelli, Sleep and previous termsynaptic homeostasis:next term a hypothesis, Brain Res. Bull. 62 (2003) 143–150; G. Tononi, C. Cirelli, Sleep function and previous termsynaptic homeostasis,next term Sleep Med. Rev. 10 (2006) 49–62]. Specifically, according to this previous termsynaptic homeostasisnext term hypothesis, wakefulness results in a net increase in previous termsynapticnext termprevious termsynapticnext term downscaling. Since previous termsynapticnext term activity accounts for a large fraction of brain energy metabolism, one of the predictions of the hypothesis is that if previous termsynapticnext term weight increases in the course of wakefulness, cerebral metabolic rates should also increase, while the opposite would happen after a period of sleep. In this study we therefore measured brain metabolic rate during wakefulness and determined whether it was affected by the previous sleep–wake history. Three groups of mice in which behavioral states were determined by visual observation were subjected to 6 h of sleep deprivation (SD). Group 1 was injected with 2-deoxyglucose (2-DG) 45 min before the end of SD, while Group 2 and Group 3 were injected with 2-DG after an additional period (2–3 h) of waking or sleep, respectively. During the 45-min interval between 2-DG injection and sacrifice all mice were kept awake. We found that in mice that slept not, vert, similar2.5 h the 2-DG-uptake was globally decreased, on average by 15–20%, compared to the first two groups that were kept awake. On average, Group 2, which stayed awake not, vert, similar2 h more than Group 1, showed only a small further increase in 2-DG-uptake relative to Group 1. Moreover, the brain regions in which 2-DG-uptake increased the least when waking was prolonged by not, vert, similar2 h showed the most pronounced decrease in DG-uptake after sleep. The data are consistent with the prediction that sleep may reset cerebral metabolic rates to a lower level. strength, while sleep is associated with


Keywords: Sleep regulation; Sleep previous termhomeostasis; Synaptic homeostasisnext term; Deoxyglucose; Mice; Brain metabolism

Abbreviations: 2-DG, 2-deoxyglucose; Cg, cingulate cortex; CC, corpus callosum; RSG, retrosplenial granular cortex; Cpu, caudate putamen; EEG, electroencephalogram; EMG, electromyogram; FD, food deprivation; GAD, glutamate decarboxylase; NREM sleep, non-rapid eye movement sleep; PB, Probst bundle; PET, positron emission tomography; REM sleep, rapid eye movement sleep; SEM, standard error of the mean; SD, sleep deprivation; SWA, slow wave activity

Written by huehueteotl

January 21, 2008 at 2:34 pm

Sleep Well And Think Better

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Don’t worry, midday snooze will not ruin a good night’s sleep – research from NewYork-Presbyterian Hospital/Weill Cornell Medical Center indicates that napping has little effect on sleep onset. And a nap today may be even beneficial for mental processing tomorrow, at least in the elderly.

Napping has little effect on sleep onset — and that a nap today may be beneficial for mental processing tomorrow, researchers say. (Credit: iStockphoto/Scott Dunlap)

People over age 60 sleep two hours less per night than their younger counterparts. Patricia Murphy and Scott Campbell, associate director and director, respectively, of the Human Chronobiology Laboratory at NewYork-Presbyterian/Weill Cornell, have evidence that a midday nap may improve daytime performance and mood in the elderly. They hold that this might be true for others too.

Their research subjects are all normal sleepers. “By learning more about how normal people sleep, we may gain a better understanding of what is happening in the bodies and minds of those with sleep disorders,” says Murphy.

Study participants spend several sessions in the sleep lab, attached to scalp electrodes and a wrist activity monitor that record their sleep and wakefulness states. They are then asked to perform arithmetic, decision-making and reaction time tests after napping and on the following day.

The subjects showed improved cognitive performance immediately after a nap and into the next day, when compared with days that didn’t include (and weren’t preceded by a day with) a nap. Napping did not seem to affect nighttime sleep.

compare:

 

J Am Geriatr Soc. 2005 Jan;53(1):48-53.!– var Menu15667375 = [ [“UseLocalConfig”, “jsmenu3Config”, “”, “”], [“LinkOut”, “window.top.location=’http://www.ncbi.nlm.nih.gov/sites/entrez?Cmd=ShowLinkOut&Db=pubmed&TermToSearch=15667375&ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVAbstractPlus&#8217; “, “”, “”] ] –>

 

Effects of a nap on nighttime sleep and waking function in older subjects.

 

Campbell SS, Murphy PJ, Stauble TN.

Laboratory of Human Chronobiology, Department of Psychiatry, Weill Cornell Medical College, White Plains, New York 10605, USA. sscampb@med.cornell.edu <sscampb@med.cornell.edu>

OBJECTIVES: To examine, in older subjects, the effect on waking function of increasing 24-hour sleep amounts by providing a nap opportunity; to assess what effects an afternoon nap may have on subsequent nighttime sleep quality and composition. DESIGN: Two-session, within-subject laboratory design. SETTING: The study was conducted in the Laboratory of Human Chronobiology at Weill Cornell Medical College. PARTICIPANTS: Thirty-two healthy men and women aged 55 to 85. MEASUREMENTS: Polysomnography (sleep electroencephalogram), cognitive and psychomotor performance, body core temperature. RESULTS: Napping had little effect on subsequent nighttime sleep quality or duration, resulting in a significant increase in 24-hour sleep amounts. Such increased sleep resulted in enhanced cognitive and psychomotor performance immediately after the nap and throughout the next day. CONCLUSION: A behavioral approach that adds daytime sleep to the 24-hour sleep quota seems worthy of consideration when presented with a situation in which physiological changes associated with aging may limit the duration of nighttime sleep.

see also:

Chronic Insomnia Can Lead To Anxiety And Depression

Chronically Lacking Sleep? You Can’t Make Up For It

sleep well….

not sleepy yet? there are more entries on this topic (yawn)…

 

Written by huehueteotl

October 31, 2007 at 11:37 am