For many
of us, bedtime can be a torment. Ironically,
when it comes to sleep, we're our own worst
enemy. Our efforts to get some rest often turn
one fitful night into full -- blown insomnia.
Blame it
on the Industrial Revolution. Or maybe on the
light bulb. But ever since man met machine,
sleep has been on the skids.
In 2001, 38 percent of
U.S. adults said they were sleeping less than
they were just five years earlier. Americans
now average seven hours in bed per night, and
close to 60 percent now report they have trouble
sleeping at least a few nights every week.
Seduced by 24-hour casinos,
Seinfeld reruns and the Internet, Americans
have plenty of diversions to keep them wired
and alert. Did we mention L.L. Bean, the store
that never closes? There's always good old worry,
the anguish of relationships gone wrong and,
right up there with the best of the sleep-wreckers,
the dour discomfort of gastroesophageal reflux.
The biggest sleep robber
of all, however, is work -- the puritan ethic
gone haywire in an era of global markets. To
accommodate the relentless pressure for productivity,
we're sleeping less and spending less time in
social and leisure pursuits; the resulting stress
can steal away even more sleep. Consider this:
We're not only missing more shut-eye, we're
having less sex, too.
To some degree, we can
sacrifice sleep to oblige other demands on our
time, but we pay a high price for the privilege.
The need for sleep, anchored in part to the
most ancient rhythms of the planet, is etched
deeply in our brains. When we interrupt the
natural rhythm of day and night for any reason
-- even reveling -- we risk setting off a cascade
of problems.
What we do at night affects
everything we do during the day -- our ability
to learn, our skills, our memory, stamina, health
and safety. Most of all, it affects our mood:
Chronic sleep disruption appears to be the single
biggest trigger for depression.
Everyone has a troubled
night sometimes, or even a run of them, which
happens to the average person about once a year.
It's part of being human, subject to stress
and worry. But it's what we do in response to
it, experts say, that determines whether we
will wind up with chronic insomnia. It turns
out that the best thing to do in response to
a bout of sleeplessness is often, well... nothing
at all.
Two
Systems, One Sleep
Recently, scientists
have come to recognize that sleep is regulated
by two entirely different systems. The knowledge
that we have two roughly parallel forces guiding
our need for sleep has opened the bedroom door
to multiple ways of treating insomnia.
One force is the sleep
homeostat. This functions like a drive that
"builds up during wakefulness in pretty much
a linear fashion and is discharged when you
sleep," explains Arthur J. Spielman, associate
director of the Center for Sleep Medicine at
New York Presbyterian-Cornell Medical College.
The homeostatic pressure to sleep depends not
only on how long you are awake but on how active
you are while awake.
But if you build up a
need for sleep in a linear fashion, one would
think you'd get sleepier as the day proceeds.
It doesn't happen quite that way. Enter circadian
rhythm, the body's biological clock. The circadian
system is tied, albeit imperfectly, to cycles
of light and dark. We have dedicated sensors
on the retina that deliver the daytime/nighttime
message directly to the pineal gland tucked
deep inside the brain. In response to darkness,
this tiny nodule of brain tissue produces the
sleep-inducing hormone melatonin, broadcasting
the sandman's message to brain areas that govern
everything from body temperature to protein
synthesis to hormone production to alertness.
Circadian rhythm guides
the body through cycles of sleep and alertness.
Ironically, it issues its strongest alerting
force in a burst lasting from 6 p.m. to 8 p.m.,
perfect for dinner-party repartee (although
you may not remember the bon mots -- short-term
memory is sharpest around 7 in the morning).
After 8 p.m., alertness begins to fade, permitting
us to doze off. This same system makes us sleepiest
in the early morning, from 4 a.m. to 6 a.m.
Stay up all night studying for an exam and circadian
forces will make you drowsy near dawn. Stick
it out for two more hours, though, and you'll
start picking up steam again. "You don't need
sleep to actually get alert," Spielman points
out.
Understanding this cycle
can help some people who have trouble falling
asleep or getting back to sleep. Manipulating
the circadian rhythm with bright lights in the
morning or melatonin in the evening, says Spielman,
can help.
By the same token, it's
possible to ramp up the sleep drive by tinkering
with the sleep homeostat. Two of the best methods
are exercise and heating the body. Grandma was
right about that warm bath before bedtime, although
she may not have known why. As it turns out,
sleep naturally follows a sharp drop in body
temperature. So lying still in bed after a hot
bath may be just what your body needs to drift
off.
Many of us complain that
we struggle to get enough sleep. But insomnia
is one of those words we toss around a bit too
freely. Experts generally apply the "30-30 rule":
It's insomnia if it takes you 30 minutes or
more to fall asleep or if you're awake for 30
or more minutes during the night -- at least
three times a week. No matter how little you
sleep, it isn't insomnia unless your nighttime
habits drag you down during the day.
Those who have trouble
falling asleep or waking up may not technically
have insomnia but instead be suffering from
"sleep-phase disorder." In this case, people
have unwittingly trained themselves to conk
out at the wrong time. It's especially common
among adolescents and college students -- those
who yield to all the siren calls for their time,
don't get to sleep before 3 a.m. or 4 a.m. and
then can't get up for classes. (If you have
insomnia four or five nights a week but not
on weekends, you probably have a phase-shift
problem.)
Sleep patterns also shift
during life. Believe it or not, "You don't want
to sleep like a baby," says Michael L. Perlis,
associate professor of psychiatry and psychology
at New York's University of Rochester and director
of the behavioral sleep medicine service there.
"You want to sleep like an adolescent." Babies
wake often; they are not yet able to consolidate
sleep into one stretch. Adolescents sleep like
there's no tomorrow.
For most people, it's
downhill from there. Marriage means accommodating
the sleep habits of another person, a biological
minefield if a late-to-bed "owl" falls in love
with an early-rising "lark" and tries to go
to bed a couple of hours earlier than his body
prefers. Childbirth brings, well, children,
and women typically learn to be vigilant during
sleep and never unlearn it; they become so fine-tuned
to noise that the habit of waking easily stays
with them the rest of their life. "Child rearing
is the number-one precipitant of insomnia,"
says Perlis.
Insomnia typically starts
innocently enough. Something gives you one bad
night -- or a few. You twist your knee and the
pain torments you all night. You're jet-lagged.
You fear your spouse is having an affair. Heartsick
or anxious, you just can't fall back asleep.
The worst is yet to come.
After one bad night, most people experience
a great deal of frustration and anxiety about
falling asleep and staying asleep. So you try
to compensate. You nap in the afternoon or go
to bed early. Or you sleep late the next morning,
or you have a couple of drinks before bed. That
only makes matters worse. You go to bed and,
without the accumulated need for sleep, you
stare at the ceiling half the night. Or -- especially
if you've had a few cocktails -- you're wide
awake at 4 a.m. Now you're even more tired and
worried about the consequences of not sleeping
than you were the day before -- while you're
at your greatest vulnerability to irrational
thought. Is this, you worry, the beginning of
decrepitude?
Pretty soon, this self-defeating
cycle takes on a life of its own. Under the
influence of anxiety, your brain learns very
quickly, without your knowledge or consent,
to associate the bedroom with wakefulness. You
lie down to rest and your brain goes on high
alert. "It has been shown that people who have
difficulty falling asleep are supersensitive
to bedroom-related stimuli," explains Perlis.
"They become physiologically aroused in the
bedroom environment" -- their nervous system
switches on just when they want it to calm down.
It's the psychophysiologic
equivalent of the perfect storm, the sudden
collision of mind, body and environment. The
actual experience, though, is more demoralizing
than dramatic: You fall asleep in front of the
television. You get up out of the armchair at
1:30 a.m. and stumble into bed. Suddenly you're
wide awake. There are now a million things to
think about, including how much you need sleep
to be at your productive best for tomorrow.
Says Perlis, "Rumination and worry -- cognitive
elements -- put gas on the fire."
No matter what sets off
the sleeplessness in the first place, faced
with bedtime, your brain kicks and screams like
a 3-year-old. "The mind can get set in the default
mode of wakefulness," says Spielman. "It gets
stuck in the scared, dangerous, vigilant zone."
There's another variety
of insomnia that results not from lack of sleep
but from a misperception: Your brain thinks
you are awake when you are asleep. Normally,
during slumber the brain's information and sensory-processing
equipment go offline. The unconsciousness of
sleep also "bleeds" slightly into wakefulness,
so that most of us can't remember falling asleep,
and we are not fully alert when we wake up.
That's why we don't remember waking up in the
middle of the night -- despite the fact that
all of us normally wake up 5 to 10 times each
night.
In some people, though,
one part of the brain stays online while the
rest is offline. Consciousness intrudes on sleep,
and these people drag themselves out of bed
in the morning, swearing, "It takes me a couple
of hours to fall asleep," and "I'm awake most
of the night." When they are hooked up to sleep
monitors, though, they seem to be sleeping just
fine.
Sleeping
off the enemy
Where insomnia is concerned,
we're our own worst enemies. No matter how sleeplessness
starts, it easily gets locked in place by our
own behavior. All of the tactics people usually
resort to in order to feel better after a bad
night -- napping, sleeping in, going to bed
early -- tend to undermine the body's natural
inclination to right itself after a short bout
of insomnia.
As a result, the most
powerful attack on the monster of insomnia is
to do nothing at all. The first and best approach
to sleeplessness is to let the sleep homeostat
right itself, without making any attempt to
compensate. It's also possible that the prompt
use of a sleeping pill -- say after a couple
of sleepless nights, rather than after several
wretched months -- can get the natural mechanism
back on track.
That's welcome news,
given what's known about the destructive power
of persistent insomnia. Chronic insomnia brings
on irritability, headaches and muscle pain.
It destroys concentration and mental well-being,
it weakens coping skills and robs vitality.
It undermines intimate relationships. On-the-job
injury rates soar 400 percent for the sleep-deprived.
Sixteen percent of absenteeism is associated
with insomnia, adding up to $50 billion a year.
"Presenteeism" -- inability to focus on the
job while there -- brings the total cost to
$150 billion. "Insomnia is the bastard cousin
to everything," says Perlis.
It also seems to be the
true mother of depression. Most depressed people
have trouble sleeping. But insomnia is not just
a symptom: It's the single best predictor of
depression, says Perlis. He has found that two
or more weeks of sleeplessness increase the
risk of a first episode of depression by 400
percent -- even for someone who has never before
been depressed. For those who have struggled
with depression before, insomnia often heralds
a recurrence.
Perlis contends that
insomnia is actually "an unleashing factor"
for depression. His longitudinal studies show
that insomnia often precedes episodes of depression
by about five weeks.
In depression, the architecture
of sleep goes awry. Normally, during the course
of the night, we gradually slip into deeper
and deeper slumber. After hitting the deepest
stage, we burst into dream sleep, marked by
dramatic brain activity and rapid eye movement
(REM). Normally, we cycle through these stages
of sleep every 90 minutes or so.
But the depressed are
on a fast track to dreamland. They dive too
quickly into REM sleep, which lasts nearly twice
as long as it does in the nondepressed. It's
also a souped up version of the REM phase. It's
more intense -- parts of the brain that deal
with emotions are more activated and the depressed
sleeper tends to fidget much more.
It seems that at least
one purpose of REM sleep is to promote the consolidation
of memory, to reinforce what we learn during
the day and integrate it into long-term memory
-- and to strip new memories of whatever emotional
charge they initially carried. "You especially
need REM sleep when you're depressed to process
negative affect," explains Michael Thase, professor
of psychiatry at the University of Pittsburgh
Medical Center and Western Psychiatric Institute
and Clinic.
But in the depressed,
"there's so much water in the dam, it can't
be contained," says Perlis. The central nervous
system stays aroused. Mental hyperactivity,
particularly intense in the amygdala and limbic
cortex of the "emotional brain," leads to an
increase in negative thoughts. The depressed
become overly biased to remember bad things.
And instead of helping to regulate mood, REM
sleep in the depressed actually worsens it.
The memory is "always as bad as it was the first
time," says Perlis. One common problem in depression
is awakening in the early morning. This may
be the body's attempt to reduce negative affect
by interrupting the last (and normally the longest)
cycle of REM sleep.
Most intriguing, the
evidence suggests that treating insomnia may
forestall a first episode of depression, or
a recurrence, and at least keep insomnia from
becoming chronic. "It may be," says Perlis,
"that if we get rid of the insomnia, we get
rid of the depression risk." And that is one
more reason not to panic the next time you find
yourself wide awake at 3 a.m.
