Humans are very much affected by biological rhythms (Circadian rhythms) and these rhythms are determined by length of daylight hours. In the center of our brain we have a structure called the pineal gland that is instrumental in regulating hormonal balances in our body based on our length of exposure to daylight. Primitive man only had to deal with light in the form of daylight or moonlight; however, modern man has a more chaotic light exposure with the advent of technology such as the electric lightbulb, computers, video games and television. We are no longer limited in our activity by the length of our available sunlight or moonlight.
Much of the early sleep studies were done at Van Cauter Sleep lab at the University of Chicago. A 1999 study there showed that chronic insomnia could trigger metabolic and endocrinological changes that mimicked aging. A 2001 study revealed that sleep deprivation could lead to insulin resistance, a risk factor for the development of adult onset diabetes. A 2002 study showed chronic sleep deprivation could decrease immune function and make a personmore susceptible to infection. A study done at the University of Chicago (published in the Annals of Internal
Medicine in December 2004) found that sleeping only 4 hours for 2 nights had the effect of decreasing the homone leptin by 18% and increasing the hormone grehlin. Grehlin is produced by the stomach and triggers the sensation of hunger. Leptin is released by fat cells and stimulates the brain to feel satiety or fullness. These 2 hormones can play a long-term role in regulation of body weight.
We have long known that women’s menstrual cycles are influenced by Circadian rhythms as menstrual cycles run on 28-day cycles, the same as the lunar cycle. A study at the University of California San Diego Sleep Lab revealed that the length of women’s menstrual cycles were altered by exposing women while they slept to artificial light around the middle of their cycles (near the time of ovulation). Hormones that trigger ovulation and even sperm maturation process are tied to natural biological or Circadian rhythms. The pineal gland is instrumental in a calibrated release of melatonin and cortisol during restorative sleep stages. Compared with good sleepers, people with insomnia secrete more cortisol in the evening before bedtime and in the first half of their sleep.
Stress is the principal cause of insomnia and affects millions of Americans. How does stress cause insomnia? Falling asleep is a natural process that involves a series of events. As we approach sleep, metabolism gradually decreases, heart rate slows and blood pressure lowers. Breathing becomes deeper and more regular; and we utilize less oxygen. The muscles in our body, which have been tense much of the day to keep us upright and moving about, begin to relax. At the same time, the processing activity of the wakeful brain shifts. The activity of neurons in the cerebral cortex slows and becomes more synchronized, indicating a transition from the complex, activated patterns of waking consciousness and toward a more homogenous, deactivated state. As a result, we stop paying attention to the sensory messages coming in from the outside world, and we slip into a peaceful, quiet sleep.
Cortisol, released during a stress response, is excitatory; it wakes us up. Blood levels of cortisol have been shown to increase between 50 and 160 percent within thirty minutes of waking; that produces the powerful jolt to awaken us up and get us moving in the morning. After that, cortisol levels should decrease as the day progresses and reach their lowest point in the evening, allowing us to rest, relax, and then drift off to sleep.
Cortisol levels are often affected by the stress of our daily hectic lives. Threatening or demanding events cause us to temporarily secrete higher levels of cortisol. Typically, that’s a good thing, because we need to be aroused and vigilant in order to face and deal with the tests and challenges that arise in our lives. However, when we experience prolonged stress, whether real or perceived, our cortisol levels get stuck at a chronically high level, that’s bad news for our bodies and emotions, and especially bad news for our ability to sleep and relax. Chronically elevated cortisol leaves us perpetually hyperaroused. Numerous studies indicate that insomnia is accompanied by excessive activation of the stress-response system during both waking hours and sleep as well. Furthermore, chronically high levels of cortisol and its precursor, adrenocorticotropic hormone, can make sleep shallow, broken, and unrestful with a delay in the onset of sleep.
Meditation, stress reduction techniques and mindfulness exercises have been proven to assist with significantly decreasing stress and improving the quality of sleep and periods of relaxation. The books I have co-authored along with Marion Ross, Ph.D. (“Shift: A Woman’s Guide to Transformation” and “SHIFT: 12 Keys to Shift Your Life”) were written after we taught the concepts in seminars and courses for 8 years and used the tools and techniques to dramatically decrease perceived stress, anxiety, and mild depression in my patients, colleagues and friends.
Wishing you a restful and joy-filled life!
Tracy Latz, M.D. (a.k.a. The Shift Doctor)
“Giving You the Keys to Shift Your Life”