Independent work # 13. Sleep.
Task 1. Read the words, skim the text and be ready to answer the questions:
R
ecurring
– повторюваний;
reduced – зменшений;
consciousness – свідомість;
decrease – зменшення;
behavior –поведінка;
wakefulness – неспання;
external – зовнішній;
environment – середовище;
rapid – швидкий;
awakening – пробудження;
alarm clock – будильник;
wound healing – зцілення ран
Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. The purposes and mechanisms of sleep are only partially clear and are the subject of intense research. Sleep is often thought to help conserve energy, but decreases metabolism only about 5–10%.
Sleep stages
In mammals sleep is divided into two broad types: rapid eye movement (REM) and non-rapid eye movement (NREM or non-REM) sleep. Humans experience such stages of sleep:
Stage 1: This is a stage between sleep and wakefulness.
Stage 2: eyes dart back and forth. This stage occupies 45–55% of total sleep in adults.
Stage 3: is called slow wave sleep. The sleeper is less responsive to the environment. This is the stage in which night terrors, nocturnal enuresis, sleepwalking occur.
The sleeper enters rapid eye movement (REM) where most muscles are paralyzed. Rapid eye movement sleep accounts for 20–25% of total sleep time. Most memorable dreaming occurs in this stage.
The stages of sleep were first described in 1937 by Alfred Lee Loomis and his coworkers. Scientific studies on sleep have shown that sleep stage at awakening is an important factor in amplifying sleep inertia. Alarm clocks, using sensing technologies, that are supposed to wake people only from light sleep, appeared on the market in 2005.
Timing. The human biological clock
Sleep timing is controlled by the circadian clock, sleep-wake homeostasis, and in humans, willed behavior. The circadian clock — an inner timekeeping, temperature-fluctuating, enzyme-controlling device — works in tandem with adenosine. Adenosine is created over the course of the day, high levels of adenosine lead to sleepiness.
Sleep deprivation
Sleep debt is the effect of not getting enough sleep; a large debt causes mental, emotional and physical fatigue, it affects immunity.
Some of the many proposed functions of sleep are as follows: restoration; wound healing; consolidation and organization of synaptic connections formed during learning and experience.
Hours by age
Children need more sleep per day in order to develop and function properly:
Age and condition Sleep Needs
Newborns (0–2 months) - 12 to 18 hours
Infants (3–11 months) - 14 to 15 hours
Toddlers (1–3 years) - 12 to 14 hours
Preschoolers (3–5 years) - 11 to 13 hours
School-age children (5–10 years) - 10 to 11 hours
Adolescents (10–17 years) - 8. 5 to 9.25 hours
Adults, including elderly - 7 to 9 hours
Pregnant women - 8 (+) hours
The siesta (nap) habit has recently been associated with a 37% reduction in coronary mortality. It can reduce stress and blood pressure.
Dreaming is the perceived experience of sensory images and sounds during sleep. Dreams can also be suppressed or encouraged by different substances.
Insomnia is a general term describing difficulty falling asleep and staying asleep. Insomnia can have many different causes, including psychological stress, a poor sleep environment, excessive mental or physical stimulation in the hours before bedtime. Insomnia is often treated through behavioral changes and cutting down on stimulants such as caffeine. Exercise (4 to 8 hours before bedtime) generally improves sleep for most people.
Task 2. Answer the questions:
1. What is sleep?
2. What can reduce stress and blood pressure?
3. How is insomnia often treated?
4. Can you name any functions of sleep?
5. Who needs more sleep per day in order to develop and function properly?
6. What does a large debt of sleep cause?
7. Who were the stages of sleep first described by?
8. What generally improves sleep for most people?
9. Can siesta(nap) reduce stress and blood pressure.
10. What causes of insomnia can you name ?