Rewire Your Brain: Think Your Way to a Better Life

paradoxical sleep
for this reason. You may 
dream that you ’ re running, and most of your organs will function as 
if you are doing exactly that. 
Although you generally go through an REM period every ninety 
minutes, most REM sleep occurs later in the sleep cycle. It consti-
tutes 25 percent of sleep time in healthy adults. 
The Sleep Cycle, or Circadian Rhythm 
Sleep is affected by daylight and darkness. Light comes in through 
the eyes, and the retina sends the information to the pineal gland, 
which is positioned in the middle of the brain. The pineal gland 
responds to light by suppressing the production of melatonin, con-
vincing the brain that it is daytime and not the time to become 
sedated. When it ’ s dark, the retina sends information to the pineal 
gland that it should produce melatonin to induce sedation. This 
cycle is called the
circadian rhythm
. 
Since the amount of light you are exposed to during the day 
affects your sleep, you should maximize your exposure to bright light 
in the daytime in order to set your circadian rhythm to match the 
natural day - night cycle of the world around you. If you suffer from 
insomnia, don ’ t use a computer in the late evening, because you ’ re 
essentially looking at light. The light of a computer screen will trick 
your brain into adjusting to a daytime pattern. Since your circadian 
rhythm can become maladapted to the actual day - night cycle, you 
need soft light a few hours before going to sleep. 
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Your circadian rhythm is tied not only to the exposure to light 
but also to your body temperature. Ideally, when you go to sleep 
at night, your body temperature should be in the process of drop-
ping. Just before you get out of bed in the morning, your body tem-
perature is on the rise. As you get out of bed and expose yourself to 
light and move around, you promote a further rise in your body 
temperature. 
If you have insomnia, you may have diffi culty regulating your 
body temperature. Your body temperature may actually increase at 
night when it should be going down. This can occur if you fail to get 
any exercise in the daytime. By exercising during the day, you can 
promote a dip in your body temperature at night.
Sleep and the Brain 
Sleep is critical for the maintenance of the brain. If you do not get 
an adequate amount of regular sleep, there are multiple defi cits. 
For example, sleep has been shown to be crucial for certain genetic 
processes, protein synthesis, and myelin formation. Without myelin, 
the neurons do not fi re effi ciently. Sleep is also critical for the syn-
thesis and transport of cholesterol, which forms a signifi cant portion 
of myelin. 
Sleep deprivation can lead to weight gain, even after just one 
week, because of an increase in the production of the hormone 
ghrelin, which promotes appetite and food intake. Simultaneously, 
there is a decline in the production of the hormone leptin, which 
curbs appetite. The increase in appetite associated with sleep loss 
tends to be for starchy, high - carbohydrate foods, sweets, and other 
high - calorie foods. Consumption of these foods by sleep - deprived 
people can be 33 – 45 percent greater than by people who are not 
sleep - deprived. This increase in appetite does not seem to be for 
fruits, vegetables, or high protein foods. 
Sleep deprivation has been shown to compromise attention, new 
learning, and memory. The longer you endure sleep deprivation, the 
more compromised these essential functions become. One of 
the most revolutionary fi ndings in neuroscience was the recent 
discovery that new neurons can grow in a certain area of the 
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130 Rew i r e
Yo u r
B r a i n
hippocampus. Studies have shown that sleep deprivation impairs 
the ability of these stem cells to grow and become new neurons. 
Synaptic consolidation (strengthening of synaptic connections) 
is critical for the formation of memories. During sleep, unstable 
memory traces are reconfi gured into more permanent ones for long -
term storage (Frank, Issa, and Stryker, 2001). Thus, during sleep the 
experiences of the day are reactivated and consolidated. 
The saying “ Why don ’ t you sleep on it? ” actually refl ects wis-
dom. Not only do you arise with a new vitality in the morning; your 
enlarged and fresh perspective is also based on having consolidated 
important memories from the previous day. It ’ s from this extension 
of the neuroplastic process — begun during the day and extended 
through sleep — that you can arrive at new insights. In fact, through-
out history there have been anecdotal stories of great insights being 
gained after a good night ’ s sleep. 
For example, this is how the Russian chemist Dmitry Mendeleyev 
conceived the idea of organizing the elements by atomic weight into 
the Periodic Table. German pharmacologist Otto Loewi, winner of the 
1936 Nobel Prize in Physiology and Medicine, reported that he 
woke during the middle of the night with the insight of how neu-
rons communicate through the chemical messengers we now call 
neurotransmitters.
Avoiding Insomnia 
Some people try to improve their sleep by using techniques that 
actually exacerbate their sleep problems. Virtually everyone has had 
insomnia at least once in their lives, and for many it ’ s an ongoing prob-
lem. Approximately half the population reports trouble sleeping once 
a week, and 15 percent have trouble sleeping two or more nights a 
week. Sleep problems are especially common among people who are 
experiencing anxiety or depression. If you ’ re tense and preoccupied, 
it ’ s diffi cult to unwind enough to fall asleep. Stress raises the levels 
of the activating neurotransmitters norepinephrine, epinephrine, 
and cortisol, which normally subside at night. If you experience 
stress, anxiety, or depression, you may keep yourself charged up and 
tense by thinking about what is waiting for you the next day. 
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Many factors contribute to insomnia, including aging, medical 
conditions, and drugs. As we age, the quality of our sleep deterio-
rates. There are also several lifestyle and environmental factors that 
contribute to insomnia, such as the following: 
•
Poor air quality in the bedroom
•
Exercise just before bedtime
•
High body temperature
•
No exercise at all
•
Caffeine
•
Daytime naps
•
Nicotine
•
Computer use in the late
•
Alcohol
evening
•
Sugar
•
Warm bedroom
•
Heavy meals before bedtime
•
Sporadic and novel noise
•
Hunger
•
Light
Caffeine causes insomnia because it blocks the adenosine recep-
tors in the brain. Adenosine is a sleep promoter, especially for 
slow - wave (deep) sleep. 
Alcohol leads to a reduction in deep sleep and REM sleep. It 
can also contribute to awakening in the middle of the sleep cycle 
because the alcohol is wearing off. It has been estimated that 10 per-
cent of all sleep problems are caused by alcohol. If you have sleep 
problems and you drink, you should stop drinking several hours 
before bedtime or not drink at all. 
If you typically wake up very early in the morning and can ’ t get 
back to sleep, you should expose yourself to bright light in the early 
morning. This will ensure that your pineal gland will not produce 
melatonin throughout the day and that your body temperature will 
be at its lowest when you sleep. If you wake up in the middle of 
the night and can ’ t get back to sleep, you should expose yourself to 
bright light in the late morning. This will encourage a lower body 
temperature in the middle of the sleep cycle and promote staying 
asleep.