Scientists have shown numerous ways in which sleep is related to memory. In a study
conducted by Turner, Drummond, Salamat, and Brown, working memory was shown to
be affected by sleep deprivation. Working memory is important because it keeps
information active for further processing and supports higher-level cognitive
functions such as decision making, reasoning, and episodic memory. The study allowed
18 women and 22 men to sleep only 26 minutes per night over a four-day period.
Subjects were given initial cognitive tests while well-rested, and then were tested
again twice a day during the four days of sleep deprivation. On the final test, the
average working memory span of the sleep-deprived group had dropped by 38% in
comparison to the control group. Wound healing has been shown to be affected by
sleep. A study conducted by Gumustekin et al. In 2004 shows sleep deprivation
hindering the healing of burns on rats. There are many reasons for poor sleep. For
example, excessive exposure to bright light within hours of bedtime or simply resisting
the urge to fall asleep can trigger a "second wind," which then can temporarily make it
difficult to fall asleep afterwards.
Dreaming is the perceived experience of sensory images and sounds during sleep, in a
sequence which the dreamer usually perceives more as an apparent participant than
as an observer.
TYPES OF SLEEP
REM (Rapid Eye Movement)
• Rapid eye movement sleep, or
REM sleep, accounts for 20–25%
of total sleep time in most human
adults. The criteria for REM sleep
include rapid eye movements as
well as a rapid low-voltage EEG.
Most memorable dreaming occurs
in this stage. At least in mammals,
a descending muscular atonia is
seen. Such paralysis may be
necessary to protect organisms
from self-damage through
physically acting out scenes from
the often-vivid dreams that occur
during this stage.
NREM (Non-Rapid Eye Movement)
• Stage N1:- It refers to the transition of
the brain from alpha waves having a
frequency of 8–13 Hz to theta waves having a
frequency of 4–7 Hz.
• Stage N2:- It is characterized by sleep
spindles ranging from 11 to 16 Hz and K-
complexes. This stage occupies 45–55% of
total sleep in adults.
• Stage N3:- It is characterized by the
presence of a minimum of 20% delta
waves ranging from 0.5–2 Hz and having a
peak-to-peak amplitude >75 μV.
OPTIMAL AMOUNT OF SLEEP
Sleep debt is the effect
of not getting enough
rest and sleep; a large
debt causes mental,
emotional and physical
fatigue. Sleep debt
results in diminished
abilities to perform high-level cognitive functions. Neuro-physiological
and functional studies have demonstrated that frontal regions of the
brain are particularly responsive to homeostatic sleep pressure.
EXPERTS SAY THE INDIRECT COSTS OF SLEEP
DISORDERS TOP $100 BILLION A YEAR.
Age And Condition Average Amount Of Sleep
Newborn Upto 18 hours
One year old 14-18 hours
One to three year old 12-15 hours
Three to five year old 11-13 hours
Five to twelve 9-11 hours
Adolescents 9-10 hours
Adults 7-8 hours
How To Sleep Well
• Nothing is more frustrating than not being able to sleep. Tossing
and turning. Your mind is racing, going over everything that
happened today. Night noises keep you awake. What can you do?
There are things you can do! Read on and learn some new
tricks to sleep well. These tips are also known as "Sleep Hygiene."
£ Sleep only when sleepy
£ Don't take naps
£ Get up and go to bed the same time every day
£ Refrain from exercise at least 4 hours before bedtime
£ Only use your bed for sleeping
£ Stay away from caffeine, nicotine and alcohol at least 4-6 hours
£ Have a light snack before bed
£ Take a hot bath 90 minutes before bedtime
Almost everyone occasionally suffers from short-term insomnia. This problem can result from stress, jet lag, diet, or
many other factors. Insomnia almost always affects job performance and well-being the next day. About 60 million
Americans a year have insomnia frequently periods of time, which leads to even more serious sleep deficits.
Insomnia tends to increase with age and affects about 40 percent of women and 30 percent of men.
• Transient insomnia lasts for less than a week.
• Acute insomnia is the inability to consistently sleep well for a period of less than a month.
• Chronic insomnia lasts for longer than a month.
• Sleep Apnea
• Sleep apnea is a disorder of interrupted breathing during sleep. It usually occurs in association with fat build-up
or loss of muscle tone with aging. These changes allow the windpipe to collapse during breathing when muscles
relax during sleep.
• Restless legs syndrome (RLS), a familial disorder causing unpleasant crawling, prickling, or tingling sensations in
the legs and feet and an urge to move them for relief, is emerging as one of the most common sleep disorders,
especially among older people.
• Narcolepsy affects an estimated 250,000 Americans. People with narcolepsy have
frequent "sleep attacks" at various times of the day, even if they have had a normal amount
of night-time sleep. These attacks last from several seconds to more than 30 minutes.
Types of insomnia
Restless Legs Syndrome
• Sleep deprivation is the condition of not having enough sleep; it can be either acute or
chronic. A chronic sleep-restricted state can cause fatigue, daytime sleepiness,
clumsiness and weight loss or weight gain. It adversely affects the brain and cognitive
function. Few studies have compared the effects of acute total sleep deprivation and chronic
partial sleep restriction. Generally, lack of sleep may result in:
• aching muscles
• bloodshot eyes
• increased blood pressure
• increased stress hormone levels
• increased risk of diabetes, fibromyalgia
• nystagmus (rapid involuntary rhythmic eye movement)
• confusion, memory lapses or loss
• Lack of sleep ups risk of colon cancer
EFFECTS ON THE BRAIN
• Sleep deprivation can adversely affect the brain and cognitive
function. A 2000 study, by the UCSD School of Medicine and the
Veterans Affairs Healthcare System in San Diego, used functional
magnetic resonance imaging (fMRI) technology to monitor activity in
the brains of sleep-deprived subjects performing simple verbal
learning tasks. The study showed that regions of the brain's prefrontal
cortex displayed more activity in sleepier subjects. Depending on the
task at hand, the brain would sometimes
attempt to compensate for the adverse effects
caused by lack of sleep.
EFFECTS ON THE HEALING PROCESS
• A 1999 study found that sleep deprivation
resulted in reduced cortisol secretion the next day,
driven by increased subsequent slow-wave sleep.
Sleep deprivation was found to enhance activity on
the hypothalamic-pituitary-adrenal axis (which
controls reactions to stress and regulates body
functions such as digestion, the immune
system, mood, sex, or energy usage) while
suppressing growth hormones. The results
supported previous studies, which observed
adrenal insufficiency in idiopathic hypersomnia.
EFFECTS ON GROWTH
• A study conducted in 2005 showed that a group of
rats which were deprived of REM sleep for five days
had no significant effect on their ability to heal
wounds, compared to a group of rats not deprived of
"dream" sleep. The rats were allowed deep (NREM)
sleep. However, another study conducted by
Gumustekin et al. in 2004 showed sleep deprivation
hindering the healing of burns on rats.
ATTENTION AND WORKING MEMORY
• Among the numerous physical consequences of
sleep deprivation, deficits in attention and working
memory are perhaps the most important; such lapses
in mundane routines can lead to unfortunate results,
from forgetting ingredients while cooking to missing a
sentence while taking notes. Working memory is
tested by such methods as choice-reaction time tasks.
IS IT A SLEEP DISORDER?
Do you . . .
Often get told by
others that you
Feel irritable or sleepy during
Feel like you
have to take a
when sitting still,
If you answered “yes” to
any of the previous
questions, you may have a
Fall asleep or feel
very tired while
Myth: The older you get, the fewer hours of sleep you need.
Fact: Sleep experts recommend a total sleep time of seven to nine hours of sleep
for the average adult. Sleep patterns change as people age, but the amount of
sleep they generally need does not. Older people may wake more frequently
through the night and may actually get less night time sleep, but their need for
sleep is no less than that of younger adults. Older people tend to sleep more during
the day because they may sleep less during the night.
Myth:-You can "cheat" on the amount of sleep you get.
Fact: Sleep experts say that most adults need between seven and nine hours
of sleep each night for optimum performance, health, and safety.
Myth: - Teens who fall asleep in class have bad habits and/or are
Fact: Teens need at least 8.5 – 9.25 hours of sleep each night, compared to an
average of seven to nine hours each night for most adults. The internal biological
clocks of teenagers can keep them awake later in the evening and can interfere
with waking up in the morning.
Myth: - Daytime sleepiness always means a person is
not getting enough sleep.
Fact: Excessive daytime sleepiness can occur even after a person
gets enough sleep. Such sleepiness can be a sign of an underlying
medical condition or sleep disorder such as narcolepsy or sleep
apnea. Symptoms should be discussed with a physician.
Myth: - During sleep, your brain rests.
Fact: The body rests during sleep. Despite this fact, the brain
remains active, gets "recharged," and still controls many body
functions including breathing.