Insomnia and Your Body Clock

Why most sleep problems are circadian related.

What is the Body Clock?
It’s not surprising that most sleep problems are the result of a body clock malfunction, since the body clock is the main sleep/wake regulator. The body clock is a cluster of cells located in the hypothalamus, near the back of the brain. The scientific name is the Suprachaismatic Nucleus (SCN), and as its name implies, it governs the release and timing of most mood, energy and sleep related hormones.

What are Circadian Rhythms?
The body clock uses signals like sunlight and darkness to know when to produce the active hormones and when to shut them down and release the nighttime withdrawal and sleep hormones. Since the body clock cycles through these hormones on a daily basis, these cycles are known as circadian rhythms (sir-kadian is Latin for ‘about a day’).

How the Body Clock Regulates Sleep
Photoreceptors called melanopsin in the retina of the eye react to signals of light and darkness and send a signal via the Retinohypothalamic Tract, a direct neural pathway to the SCN. The SCN uses this input to regulate the suppression or release of daytime and nighttime hormones. If the SCN gets enough light, it suppresses melatonin and several other endogenous sleep inducing neurotransmitters. In the absence of light, the SCN suppresses the active hormones and produces the nighttime withdrawal hormones.

How We Fall Asleep
In the evening time the body clock recognizes that light is diminishing, and it shuts down the production of serotonin, adrenalin, cortisol and other active hormones. As darkness increases, the body clock tells the pineal gland to convert available serotonin into melatonin. The increase in melatonin causes blood vessels to constrict and pulls the blood away from the limbs and closer to the vital organs. Brain activity, heart rate, blood pressure and body temperature all decrease. In essence, the body slows down and slips into a state of semi-consciousness. During the night’s darkness, the body clock continues to increase melatonin production and body temperature continues to drop.

Why We Wake Up
In the pre-dawn hours the body temperature has reached its minimum, and morning twilight signals the body clock to stop producing melatonin. The body clock also signals the endocrine system to begin producing cortisol, serotonin and other powerful alertness hormones. Cortisol acts as a power surge, and cortisol levels are highest in the early morning. About an hour after cortisol levels rise the body is able to wake up.

How We Damage The Sleep Cycle: What causes our body clocks to malfunction?

Regularity
As Dr. Smolensky reports in The Body Clock Guide To Better Health, our bodies crave regularity. Although we may have been able to stay up late on the weekends in our youth, we pay the price later in life. Any activity that takes us away from a consistent sleep/wake routine will throw off our body clocks. For example, we shouldn’t be surprised that we suffer from Sunday night insomnia if we stayed up late and slept in on the weekend.

Refusing to sleep when the body clock wants to creates conflicting signals; it delays the body’s ability to produce melatonin and cause the body temperature to drop, both critical factors for inducing and maintaining sleep. A regular schedule helps the body temperature to drop when it is supposed to. Those with sleep problems have body temperatures that drop more than two hours later than normal.

Delayed Sleep Insomnia
The body clock tends to naturally delay (or run a bit slow) anyway, and once it is out of sync, it is very difficult to reset it without medical intervention such as light therapy. (Most adults on average have a body clock that runs between 24.5 - 25.5 hours.) This type of insomnia makes it difficult to fall asleep, can cause frequent nighttime awakenings, and morning exhaustion. If someone has a chronic problem falling and staying asleep, he or she will benefit quickly from light therapy but may have to use light consistently for several months or years.

Age and Sex
Age and sex are some of the most significant factors of circadian related sleep disorders. The body clock changes with age. For most people from adolescence to middle age, the body clock runs too slow. Women’s body clocks tend to run slower than males, and they tend to start having difficulty at an earlier age. As women reach midlife, and most significantly by menopause, their body clocks tend to speed up. Men tend to have delayed body clock problems during late adolescence and even up to their early sixties, at which time they too begin to struggle with advanced or fast running body clocks.

Puberty & Young Adulthood: Late night insomnia
During puberty, the body clock overproduces melatonin in order to allow the body time to rest and recuperate from the significant growth and changes that are taking place. As a result, adolescents’ body clocks tend to delay. Junior high and high school kids start struggling to wake up in the morning because their body clocks won’t produce the ‘waking hormones’ for another few hours. Because their body clocks have delayed, they will not be able to fall asleep until later at night. This body clock cycle adapts easily to late night weekends and partying, but unfortunately compounds the delayed circadian rhythm disorder.

Many people in this age category will suffer worse in the winter, as their body clocks receive an increased stimulus of darkness, which over produces melatonin and further delays the body clock. This is the main reason that Seasonal Affective Disorder (SAD) is usually first seen in younger women and young men.

Midlife: Begins early morning awakening & evening fatigue
Almost all body clocks will change with time. Although it happens earlier to women than men, those who previously had no problem will find they suffer from an advanced circadian rhythm. They begin to notice more early morning awakenings with difficulty falling asleep again. Morning time seems to be the best time of day, but evenings and late nights become increasingly more difficult to stay alert and feel energetic.

The Golden Years: Early morning insomnia
By the time most people reach their sixties, their body clocks are running too fast. Most seniors experience chronic early morning insomnia because their body clocks have produced melatonin and other sleep hormones too early during the evening and can’t maintain a full sleep cycle. Retirement communities and nursing homes’ greatest staffing problem is during the night shift because most patients awaken in the wee hours of the morning.

Trauma, Stress & Depression
Other factors such as surgery, stress, physical or mental trauma and depression can cause the body clock to malfunction. In these cases, the body clock will usually delay or advance, depending on age. In most cases, stress and depression affect the onset of sleep and the ability to stay asleep at night. Those who suffer from bipolar disorders and ADHD have delayed circadian rhythms and need specialized morning light. In fact, medical reviews now acknowledge that circadian rhythm disorders are an underlying factor in most mood related disorders.

Lack of Light
Winter darkness, darker climates and even environmental lighting can cause circadian related sleep disorders and mood problems. When the body clock doesn’t receive the needed light and dark signals at the right time of day, it will not function properly and will either speed up or slow down, depending on age. In some cases, the body clock may not delay or advance, but becomes weak and will not produce the right amount of hormones at the right time. In this case, one may not notice a sleep problem per se, but optimal functioning during the day is compromised, and he/she will probably experience fatigue.

Menstrual Cycles and PMS
In addition to controlling the daily sleep/wake cycles, the body clock is responsible for regulating menstrual cycles. The body clock signals the ovaries to develop the egg sac, and again about 14 days later, the body clock starts the release of the egg. Progesterone and estrogen production are both signaled by the body clock. During the late luteal phase, just before menstruation, the body clock tends to advance, causing early morning awakening in some women as well as depleting normal levels of serotonin. Evening light administered one week prior to menstruation has been shown to alleviate the symptoms of PMS and restore proper sleep patterns.

Darkness may also be one of the major reasons menstrual cycles become irregular. Women who live near the equator or in sunny regions are more fertile and have stronger and more regular menstrual patterns than women who live in northern regions or spend more time indoors. Also, menstrual cycles during the darker winter months are longer than in the summer.

Specialized Light Regulates Circadian Rhythm Disorders.

In the early 1980’s researchers at the National Institute of Health discovered circadian rhythms and their effect on sleep disorders. In 1984, the NIH also discovered that specialized bright light could quickly control circadian related sleep disorders. Thousands of studies in light therapy have confirmed that specialised light is the most effective regulator of our circadian rhythms.More recent discoveries have also shown that specific wavelengths (470nm) of blue light are responsible for suppressing melatonin produced by the pinel gland and shifting circadian rhythms. The American Academy of Sleep Medicine recommends specialised light therapy as a first line treatment for body clock sleep disorders.