_______________________________________________________________________________________________________________________________


Sleep: A Dynamic Activity


Until the 1950s, most people thought of sleep as a passive, dormant part of our daily lives. We now know that our brains are very active during sleep. Moreover, sleep affects our daily functioning and our physical and mental health in many ways that we are just beginning to understand.

Nerve-signaling chemicals called neurotransmitters control whether we are asleep or awake by acting on different groups of nerve cells, or neurons, in the brain. 


How Much Sleep Do We Need?


The amount of sleep each person needs depends on many factors, including age. Infants generally require about 16 hours a day, while teenagers need about 9 hours on average. For most adults, 7 to 8 hours a night appears to be the best amount of sleep, although some people may need as few as 5 hours or as many as 10 hours of sleep each day. Women in the first 3 months of pregnancy often need several more hours of sleep than usual. 

People tend to sleep more lightly and for shorter time spans as they get older, although they generally need about the same amount of sleep as they needed in early adulthood. About half of all people over 65 have frequent sleeping problems, such as insomnia, and deep sleep stages in many elderly people often become very short or stop completely. This change may be a normal part of aging, or it may result from medical problems that are common in elderly people and from the medications and other treatments for those problems.

Experts say that if you feel drowsy during the day, even during boring activities, you haven't had enough sleep. If you routinely fall asleep within 5 minutes of lying down, you probably have severe sleep deprivation, possibly even a sleep disorder. Micro sleeps, or very brief episodes of sleep in an otherwise awake person, are another mark of sleep deprivation. In many cases, people are not aware that they are experiencing microsleeps. The widespread practice of "burning the candle at both ends" in western industrialized societies has created so much sleep deprivation that what is really abnormal sleepiness is now almost the norm.


Sleep and Disease

Sleep and sleep-related problems play a role in a large number of human disorders and affect almost every field of medicine. For example, problems like stroke and asthma attacks tend to occur more frequently during the night and early morning, perhaps due to changes in hormones, heart rate, and other characteristics associated with sleep. Sleep also affects some kinds of epilepsy in complex ways.Neurons that control sleep interact closely with the immune system. As anyone who has had the flu knows, infectious diseases tend to make us feel sleepy. This probably happens because cytokines, chemicals our immune systems produce while fighting an infection, are powerful sleep-inducing chemicals. Sleep may help the body conserve energy and other resources that the immune system needs to mount an attack.


Sleeping problems occur in almost all people with mental disorders, including those with depression and schizophrenia. People with depression, for example, often awaken in the early hours of the morning and find themselves unable to get back to sleep. The amount of sleep a person gets also strongly influences the symptoms of mental disorders. Sleep deprivation is an effective therapy for people with certain types of depression, while it can actually cause depression in other people. Extreme sleep deprivation can lead to a seemingly psychotic state of paranoia and hallucinations in otherwise healthy people, and disrupted sleep can trigger episodes of mania (agitation and hyperactivity) in people with manic depression.


_______________________________________________________________________________________________________________________________

When people talk about intelligence tests, they often discuss "genius scores." What exactly constitutes a genius score on a measure of intelligence? In order to understand the score, it is important to first learn a little bit more about IQ testing in general.

Today's intelligence tests are based largely on the original test devised in the early 1900's by French psychologist Alfred Binet. In order to identify students in need of extra assistance in school, the French government asked Binet to devise a test that could be used to discover which students most needed academic help.

Based on his research, Binet developed the concept of mental age. Certain questions he posed were easily answered by children of certain age groups. Some children were able to answer questions that were typically answered by children of an older age - these children had a higher mental age than their actual chronological age. Binet's measure of intelligence was based on the average abilities of children of a particular age group.

Understanding IQ Scores

IQ scores generally follow what is known as the Bell Curve. In order to understand what the score on an IQ test means, there are a few key terms that you should know:

  • Bell Curve: When IQ scores are plotted on a graph, they typically follow a bell-shaped curve. The peak of the "bell" occurs where the majority of the scores lie. The bell then slopes downward to each side - one side representing scores that are lower than the average, the other side representing scores that are above the average. An example of a bell curve can be seen in the image above.

  • Mean: The average score. The average is calculated by adding all of the scores together, then dividing by the total number of scores.

  • Standard Deviation: A measure of variability in a population. A low standard deviation means that most of the data points are very close to the same value. A high standard deviation indicates that the data points tend to be very spread out from the average. In IQ testing, the standard deviation is plus or minus 15.

TODAY'S QUESTION:

 Q: Acids are found in many common chemicals, including foods. Acids taste: