Archive for June, 2007

Those persons who are labeled “night owls” report more pathological symptoms related to insomnia, despite many having the opportunity to compensate for their nocturnal sleeplessness by extending their time in bed and being able to gain more total sleep time, according to a study published in the Journal of Clinical Sleep Medicine (JCSM).

The study, authored by Jason C. Ong, PhD, and colleagues at Stanford University, consisted of 312 patients, who were categorized as morning, intermediate and evening chronotypes based upon scores on the Morningness-Eveningness Composite Scale.

Group comparisons were made on self-report measures of nocturnal sleep, sleep period variability and waking correlates and consequences of insomnia.

Compared to the morning and intermediate types, people with insomnia who prefer evening activities (i.e., “night owls”) reported the most sleep/wake irregularities and waking distress, even after adjusting for severity of sleep disturbance.

“Our findings indicate that further research should investigate the relationship between circadian rhythms and insomnia, especially with the severity of the ‘night owl’ group,” said Ong.

“These factors may serve to perpetuate the insomnia disorder, and might be particularly important to consider when treating this subgroup of insomniacs.”

According to the new study, it is found that there is an association between a form of sleep disorder and the development of dementia.

People with a form of sleep disorder, which is REM behavior disorder (RBD), have high probability of developing dementia, Parkinsonism, or multiple system atrophy because all these conditions appear to generate from a similar neurodegenerative origin.

Patients with REM behavior disorder exhibit early signs of an evolving neurodegenerative disease which in most cases appear to be caused by some mishap of the synuclein protein.

Synuclein proteins are associated with synapses in the brain and clumps of abnormal alpha-synuclein protein are present in some forms of dementia. The problem is not present in the synuclein gene itself but it happens to the protein following gene expression.

Researchers examined older males who strike out violently, often yelling, when they entered REM sleep. For many years of research, researchers saw many of them develop symptoms of dementia.

It does not mean someone has this condition when they notice violent movements during sleep. The danger with REM behavior disorder is that patients can hurt themselves or their spouses during the act out behaviors.

Sleep not only protects memories from outside interferences, but also helps strengthen them, according to research that will be presented at the American Academy of Neurology’s 59th Annual Meeting in Boston, April 28 May 5, 2007.

The study looked at memory recall with and without interference (competing information). Forty-eight people between the ages of 18 and 30 took part in the study. All had normal, healthy sleep routines and were not taking any medications.

Participants were divided evenly into four groups a wake group without interference, a wake group with interference, a sleep group without interference and a sleep group with interference. All groups were taught the same 20 pairs of words in the initial training session.

The wake groups were taught the word pairings at 9 a.m. and then tested on them at 9 p.m. after 12 hours awake. The sleep groups were taught the word pairs at 9 p.m. and tested on them at 9 a.m. after a night of sleep.

Just prior to testing, the interference groups were given a second list of word pairs to remember.

Gambling is a risky activity that can potentially result in the loss of a significant amount of money. Sleep deprivation can adversely affect a person’s decision-making at a gambling table by elevating the expectation of gains and making light of one’s losses following risky decisions.

To understand the neural underpinnings of risky decision making under conditions of sleep deprivation, Vinod Venkatraman and colleagues of Duke University studied healthy volunteers as they underwent functional magnetic resonance imaging (fMRI), the use of MRI to measure the haemodynamic response related to neural activity in the brain or spinal cord of humans.

The authors found that the nucleus accumbens, an area in the brain involved with the anticipation of reward becomes selectively more active when high risk-high payoff choices were made under conditions of sleep deprivation.

Further, the number of high risk decisions did not increase with sleep deprivation, but the expectation of being rewarded for making the high risk gamble was elevated.

Allied to this finding was the observation that there was an attenuated response to losses in the insula, a part of the brain involved with evaluating the emotional significance of an event.

Parkinson’s disease is well-known for its progression of motor disorders: stiffness, slowness, tremors, difficulties walking and talking.

Less well known is that Parkinson’s share other symptoms with narcolepsy, a sleep disorder characterized by sudden and uncontrollable episodes of deep sleep, severe fatigue and general sleep disorder.

Now a team of UCLA and Veterans Affairs researchers think they know why  the two disorders share something in common: Parkinson’s disease patients have severe damage to the same small group of neurons whose loss causes narcolepsy.

The findings suggest a different clinical course of treatment for people suffering with Parkinson’s that may ameliorate their sleep symptoms.

In their report in the May issue of the journal Brain, Jerry Siegel, professor of psychiatry and biobehavioral sciences at the Semel Institute for Neuroscience and Human Behavior at UCLA, assistant resident neurobiologist Thomas C. Thannickal and associate research physiologist Yuan-Yang Lai have determined that Parkinson’s disease patients have a loss of up to 60 percent of brain cells containing the peptide hypocretin.

In 2000, this same group of UCLA researchers first identified the cause of narcolepsy as a loss of hypocretin, thought to be important in regulating the sleep cycle.