REM
Sleep
REM sleep is a deep sleep phase marked
by periods of rapid eye movement and intense dreaming,
possibly related to the process “memory consolidation” wherein
the brain sorts through the previous day’s experiences
to form long-term memories. As the body cycles between
nonREM and REM sleep throughout the night, each recurring
REM cycle last longer than the previous one, with the
final REM phase lasting up to an hour.
Humans spend almost 50 percent of
their total sleep in stage 2 sleep, about 20 percent
in REM sleep, and the remaining 30 percent in the other
stages. Infants, by contrast, spend about half of their
total sleep time deep in REM sleep.
Age-Related
Sleep Problems
One of the biggest problems facing
adults is the inability to achieve a deep, restful
sleep, and by age 64 about half of all adults report
some form of sleeping disorder.3 Age-related sleep
disorders have been linked to biochemical changes in
the body’s internal clock that alter the normal
response to external light cues (i.e. sunset, sunrise).
This results in older people going to sleep earlier
in the evening and waking up earlier in the morning.
Older sleepers also tend to wake up more frequently
during the night, resulting in fragmented sleep.
Sleep
Loss in Middle Age
In the first study of its kind, sleep
researchers at the University of Pittsburgh have shown
that altered sleep patterns actually begin in what
many consider to be their most productive years – middle
age. This finding surfaced as researchers tracked the
sleeping patterns of 110 healthy volunteers, aged 20
to 59 years. They found that the quality and duration
of sleep changed dramatically between the mid-20s and
the mid-50s, with subjects going to bed and waking
up earlier. The subjects also slept less, woke up more
often during the night, and experienced fewer stages
of deep sleep.4
According to study author, Dr. Julie
Carrier, “Middle age is a turning point for sleep.
Some sleep patterns have already changed significantly
by the time an average adult reaches age 30.” Dr.
Carrier observed that these changes are most likely
tied to gradual age-related changes in features of
the biological clock. “We need to learn where
the system breaks down. If we are able to find out
what is causing the biological clock to change with
age, we may be able to discover ways to overcome these
changes and help get these people back on track.”
Progressive
Loss of Melatonin
As sleep scientists continue to investigate
the body’s biological clock, existing research
has already shown how disrupted sleep patterns are
linked to significant age-related alterations in hormone
production. One well-established example is the age-related
decline in melatonin, the principal hormone produced
by the pineal gland (Fig. 1). Melatonin is a vital
neurohormone involved in regulating the neuroendocrine
system and controlling essential functions such as
metabolism, sex drive, appetite, and sleep. Melatonin
also exerts powerful antioxidant activity and plays
a key role in the immune system by preventing the proliferation
of cancer cells.
As mentioned earlier, melatonin production
and release is controlled by the body’s “biological
clock” (suprachiasmatic nucleus) in response to changes
in daily light/dark cycles. Melatonin levels are known to
drop significantly after childhood and serve as one of the
most dramatic markers of biological aging known. By the age
of 60, nighttime melatonin production practically ceases,
and by age 80 melatonin plasma levels are barely detectable.
Obesity
Linked to Lack of Sleep
Sleep scientists have identified additional
links between disrupted sleep cycles and age-related alterations
in hormonal levels. In one study, researchers from the Stan-ford
University School of Medicine have shown that getting less
than 8 hours of sleep leads to increased levels of ghrelin,
a hormone produced by the stomach that makes people hungry,
slows metabolism and decreases the body's ability to burn
fat.5 Ghrelin levels in the blood spike before meals and
drop afterward. People given ghrelin injections become voraciously
hungry, consuming up to 30 percent more calories than they
normally would.6
The Stanford researchers also discovered
that inadequate sleep results in lower levels of another
appetite hormone, leptin. In contrast to ghrelin, lower levels
of leptin signal the body that it is starving, further increasing
appetite and the drive to consume extra calories.
The Stanford study revealed a 14.9 percent
increase in ghrelin levels, and 15.5 percent decrease in
leptin levels in people who consistently slept for only five
hours, compared with those who slept for eight. These findings
are supported by previous studies that show that people who
get less than four hours of sleep each night are 73 percent
more likely to be obese than normal sleepers.
Drop
in Growth Hormone Linked
to Slow Wave Sleep
In related news, researchers from the University
of Chicago School of Medicine have associated sleep loss
with the age-related drop in human growth hormone (GH). Growth
hormone is normally released during the most restful phase
of slow wave sleep (SWS). Growth hormone plays a vital role
in human health, stimulating bone growth, immune function,
amino acid uptake, protein synthesis, and muscle glucose
uptake. Growth hormone also induces the burning of fat from
adipose tissues and plays a key role in maintaining cardiovascular
health.
Reduction of growth hormone in aging humans
is associated with immune system malfunctions, increased
body fat deposits, a loss of muscle tone and overall physical
strength, thinning of skin, and diminished sexual drive.
When the Chicago researchers monitored
the sleep patterns of 149 healthy men, aged 16 to 83 years,
over a period of 14 years they discovered that the total
amount of time spent in slow wave sleep (SWS) dropped from
19% of total sleep in early adulthood to only 3% by midlife.
This decline in restorative slow wave sleep was matched by
major declines in the secretion of human growth hormone.7
Elevated
Cortisol and REM
In the same study the Chicago researchers
noted a significant increase in evening levels of cortisol
in subjects 50 years and older. These elevated cortisol levels
were associated with increased sleep fragmentation and further
declines in REM sleep. Cortisol, the body’s principal
anti-inflammatory hormone, is typically released by the adrenal
glands in response to stress. While some cortisol is necessary,
chronically elevated cortisol levels (hypercortisolemia)
contribute to obesity, hypertension, reduced glucose tolerance
(a contributing factor in developing diabetes), loss of bone
density, decreased muscle mass and increased neuronal death
of brain cells.
Sleepless
Rats Reveal Problem
in Biological Clock
Two recent animal studies seem to confirm
that problems within the body’s cellular clock serve
as a crucial source of age-related sleep problems while suggesting
that the clock can be “reset” to more youthful
levels – at least in aged rats.
In the first study, researchers at Washington
University in St. Louis examined cells from the suprachiasmatic
nucleus (SCN) that are responsible for generating circadian
rhythms. They discovered that the electrical activity of
these “clock cells” in older rats was irregular
when compared with the activity of timing cells in young
and middle-aged animals. According to Erik Herzog, Ph.D.,
assistant professor of biology at Washington University, "In
the case of the aged rats, many of them showed fragmented
behavioral rhythms. The cells in the older rats were still
rhythmic, but showed bouts of activity when they normally
would have rested, and inactivity when the young animals
were active. So, the rats, like elderly humans, took naps
when they would have normally been active. Remarkably, the
cells in their biological clock reflected this behavior.”8
Research
Links Healthy Biological
Clock to Longevity
In a related study supported by the National
Institute on Aging in the US and the Natural Sciences and
Engineering Research Council in Canada, researchers transplanted
fresh brain cells harvested from the suprachiasmatic nucleus
of young hamsters into the biological clocks of aging hamsters.
Normally, once a hamster’s biological clock has begun
to deteriorate, death occurs within three months. However,
after the researchers transplanted the new “clock” into
hamsters whose own clocks had begun to deteriorate, the animals
lived an average of four months longer than hamsters without
the transplant – equivalent to increasing their lifespan
by an astonishing 20 percent.
According to psychologist Martin Ralph
of the University of Toronto, other therapies might achieve
similar results. "If the function of the clock can be
mimicked by a structured lifestyle, such as more light during
the day and darkness at night, then this will work in the
same direction as the transplant works in hamsters.”9
Poor
Sleep Linked to Early Death in Older Adults
Sleep disturbances have been shown to double
the risk of death for healthy older adults compared to more
restful seniors, according to new research. Lying awake for
30 minutes or longer and spending a smaller percentage of
the night asleep boost the risk of death among older adults,
according to Mary Amanda Dew, Ph.D., and colleagues at the
University of Pittsburgh School of Medicine.
Older adults who sleep poorly tend to have
a diminished quality of life, but the study by Dew and colleagues
suggests that sleep disturbances can have a much more serious
effect on health.
"Interventions that optimize or protect
sleep initiation and sleep quality in old age might not only
add quality of life but prolong life as well,” Dew
says.
In eight different studies between 1981
and 1997, the researchers used EEG monitors to observe sleep
patterns in 185 healthy adults 60 to 90 years old. Dew and
colleagues then collected follow-up information to find which
study participants had died by the year 2001.
The 66 adults who had died were more likely
in the earlier sleep studies to lie awake for long periods,
to sleep less "efficiently" through the night and
to have abnormally high or low amounts of REM sleep, compared
to study participants who were still living at the time of
follow-up.
The link between poor sleep and earlier
death remains significant, even after adjusting for the influence
of age, gender and existing health problems, the researchers
note.10
Sleep
Cycle™ for a Deeper Night’s Sleep
Though people frequently tend to focus on
falling asleep quickly, a far better indicator sleep quality
is the ability to wake up feeling refreshed, energized and
restored the following day. Consequently, Sleep Cycle is
not intended to act like a fast-acting sleeping pill that
knocks people out quickly. Instead, Sleep Cycle works by
gently promoting a state of calm as it initiates the natural
process of falling asleep. Over time, Sleep Cycle conditions
and improves the overall quality of sleep by gradually extending
the duration of deep, Slow Wave Sleep (SWS) and shortening
the length of time it takes to fall into a restful slumber.
Sleep Cycle achieves this by combining
traditional herbal extracts with state-of-the-art modern
nutrients to deliver a unique, safe and highly effective
natural sleep aid.
Sleep Cycle begins with two nutritional
compounds, melatonin and 5-HTP, that have been shown to aid
in resynchronizing the body’s biological clock to promote
healthier sleep rhythms. Sleep Cycle also contains a well-known
combination of natural plant extracts that have been used
for centuries to promote deep, restful sleep, including Hops,
Lemon balm, Passionflower, Valerian root, Angelica, Jujube,
and Polygala. Additionally, Sleep Cycle contains L-Theanine,
an amino acid derived from green tea prized for its ability
to promote calm and relax the mind.
Finally, Sleep Cycle contains a new, clinically
researched herbal ingredient, Wulinshen, that is
derived from the traditional herb, Xylaria Nigripes by way
of a proprietary pharmaceutical extraction and formulation
process. This proprietary compound, found only in Sleep Cycle,
provides critical and often depleted nutrients required by
the brain to assist biochemical processes involved in promoting
restful, deep sleep. Wulinshen contains significant amounts
of glutamic acid, gamma-aminobutyric acid (GABA) and glutamate
decarboxylase. GABA's main function is to inhibit excitatory
neuro-activities by exerting a tranquilizing effect on the
central nervous system. Glutamate decarboxylase (GAD) supports
the synthesis of GABA, while glutamic acid assists the uptake
of GABA to specific brain cell receptors.
Summary
As sleep scientists continue to investigate
the body’s biological clock, existing research has
already shown how disrupted sleep patterns are linked to
significant age-related alterations in hormone production.
One well-established example is the age-related decline in
melatonin, the principal hormone produced by the pineal gland
(Fig. 1). Melatonin is a vital neurohormone involved in regulating
the neuroendocrine system and controlling essential functions
such as metabolism, sex drive, appetite, and sleep. Melatonin
also exerts powerful antioxidant activity and plays a key
role in the immune system by preventing the proliferation
of cancer cells.
References
1. 1. NIH
Office of Communications and Public Liaison, National
Institute of Neurological Disorders and Stroke
2. http://www.sleepfoundation.org
3. E. J. W. Van Someren. “Circadian and sleep disturbances
in the elderly.” Experimental Gerontology, Volume 35,
Issues 9-10, December 2000, Pages 1229-1237.
4. University Of Pittsburgh Medical Center. “Deterioration
Of Sleep During Middle Age Related To Changes In The Biological
Clock.” ScienceDaily 25 June 1998.
5. Stanford University Medical Center. “Stanford Study
Links Obesity To Hormonal Changes From Lack Of Sleep.” ScienceDaily
9 December 2004.
6. Plasma ghrelin levels after diet-induced weight loss or
gastric bypass surgery. N Engl J Med. 2002 May 23;346(21):1623-30.
7. Age-Related Changes in Slow Wave Sleep and REM Sleep and
Relationship With Growth Hormone and Cortisol Levels in Healthy
Men Eve Van Cauter, PhD; Rachel Leproult, MS; Laurence Plat,
MD JAMA. 2000;284:861-868.
8. Washington University In St. Louis (2001, August 14). Sleepless
Aged Rats Show Biological Clock Problems. ScienceDaily.
9. University Of Toronto (1999, March 29). Research
Links Healthy Biological Clock To Longevity. ScienceDaily.
10. Center For The Advancement Of Health, 2003, February
4.
