Dr. Hibbs describes a male patient suffering from many effects of stress, including fatigue and constipation. The patient relied heavily on coffee to keep him going physically and had developed chronic adrenal fatigue. Dr. Hibbs took him off caffeine and sugar, which are both stimulants and were taxing his system. Appropriate exercise and dietary changes were made and he was put on adrenal supportive supplements containing glandular tissue, herbs, and nutrients. His bowel habits normalized quickly and remained that way when he stopped the adrenal supplements several months later.
Alternative Medicine by Burton Goldberg, page 688

The adrenal exhaustion/stress/fatigue/hypoglycemia syndrome is tied to caffeine use as well. Caffeine has an overall effect of increasing blood sugar (especially when it is sweetened), as it stimulates the adrenals. Both stress and sugar use tend to pressure and weaken the adrenal function. Recovery from the resulting fatigue requires rest, stress reduction, and sugar avoidance, but caffeine can override this fatigue and restimulate the adrenals. This process can eventually lead to chronic fatigue, adrenal exhaustion, and subsequent inability to handle stress and sugar intake. Caffeine will then be of little help.
Staying Healthy With Nutrition by Elson M Haas MD, page 942

Research is revealing that cortisol and DHEA, both produced in the adrenal cortex, hold an inverse relationship. As serum cortisol increases, DHEA levels fall. It may be that stress and caffeine create such a high need for cortisol that the exhausted adrenals simply cannot maintain production of DHEA at optimal levels.
Caffeine Blues By Stephen Cherniske MS, page 68

Caffeine is undeniably an effective central nervous system stimulant. It stimulates the brain, increases the secretion of adrenaline (epinephrine), and boosts heart rate. Although relatively safe, long-term use in excess of 250 to 300 mg daily may cause numerous health problems. Caffeine has been known to raise blood-cholesterol levels, deplete B vitamins, irritate the stomach and bladder, exhaust the adrenals, and possibly lead to breast and prostate problems.
Off The Shelf Natural Health How To Use Herbs And Nutrients To Stay Well By Mark Mayell, page 112

Far too many people overconsume caffeine, however. This occurs, I think, because people simply do not have enough natural energy. Instead of getting enough sleep, nutrients, and exercise to provide the energy they need, people depend upon caffeine to push them through the day. The short-term price for this dependency is nervousness, irritability, insomnia, and a "rebound effect" of lethargy and mental lassitude. The long-term price is burnout of the adrenal glands, and a body that has been exhausted by artificial stimulation.
Brain Longevity by Dharma Singh Khalsa M.D. with Cameron Stauth, page 266

Fatigue, childbirth, or injury to the kidney-adrenal area, also steroid drugs or excess use of stimulants, including caffeine, to the point of adrenal exhaustion, can all harm sexual strength for men and women alike. Muscles can become weak. Blood circulation and nerve sensitivity can become impaired. These are important factors in sexual strength. Some sexologists think of the vagina as a muscle.
Asian Health Secrets by Letha Hadady DAc, page 423

According to Leon Chaitow, N.D., D.O., dizziness when standing after sitting or lying down can be an indication of adrenal exhaustion. The individual should take action to restore adrenal health by stopping the use of stimulants (caffeine, tobacco, alcohol) and via rest and normalization of lifestyle and nutritional balance.
Alternative Medicine by Burton Goldberg, page 1014

"In other words, caffeine affects your body just like any drug: Addiction and withdrawal"

Caffeine is the most widely used drug in the world. Studies show that abstinence induces a withdrawal syndrome of fatigue, headache and drowsiness within 24 hours and lasts about a week, on giving up the habit.
Bartrams Encyclopedia of Herbal Medicine by Thomas Bartram, page 83

The second way that caffeine contributes to depression is, of course, the withdrawal reaction, the most prevalent symptoms being headache, depression, and fatigue. Three facts are important to grasp in regard to withdrawal. First of all, each of the symptoms compounds or magnifies the depressive effect. Secondly, withdrawal can occur even in light caffeine users. And third, withdrawal reactions can be evident even when caffeine is withheld for just a few hours. Some people feel depressed or anxious if they’re simply late for their morning or afternoon cup. That’s not only a powerful motivation to consume the beverage, but it also creates an often-unidentified source of background stress.
Caffeine Blues By Stephen Cherniske MS, page 112

Almost all of the research that has been done on caffeine agrees that it is definitely physically addictive. It is a mood-altering central nervous system stimulant. Though milder in its effects, caffeine manipulates the same neurochemical channels that amphetamines, cocaine, and heroin do. Overuse of caffeine can result in a variety of symptoms, including irregular heartbeat, sleeplessness, headaches, nervousness, tremors, irritability, and depression. Withdrawing from heavy caffeine use can cause symptoms, too, principally a nagging headache that is unaffected by aspirin or other over-the-counter painkillers, as well as fatigue, muscle pain, lethargy, and feelings of depression. To break a caffeine addiction, therefore, it is best to cut down gradually to avoid an uncomfortable withdrawal period.
Prescription For Dietary Wellness by Phyllis A Balch, page 230

Caffeine works by mimicking a hormone that tells the adrenal glands to crank out more adrenaline. The adrenal glands think there is a stressful situation and that they are supposed to be making more adrenal hormone.
Herbal Defense by Ralph T Golan ND, page 280

A dosage of 50 to 100 mg caffeine, the amount in one cup of coffee, will produce a temporary increase in mental clarity and energy levels while simultaneously reducing drowsiness. It also improves muscular-coordinated work activity, such as typing. Through its CNS stimulation, caffeine increases brain activity; however, it also stimulates the cardiovascular system, raising blood pressure and heart rate. It generally speeds up our body by increasing our basal metabolic rate (BMR), which burns more calories. Initially, caffeine may lower blood sugar; however, this can lead to increased hunger or cravings for sweets. After adrenal stimulation, blood sugar rises again. Caffeine also increases respiratory rates, and for people with tight airways, it can open breathing passages. Caffeine is also a diuretic and a mild laxative.
The New Detox Diet by Elson M Haas MD, page 30

Caffeine and nicotine overstimulate the adrenal glands. When these substances, other stressors, and a generally poor diet are combined, the adrenals can enter into a state of emergency. They become depleted of important vitamins, such as B-complex vitamins and vitamin C.
Complete Encyclopedia Of Natural Healing by Gary Null PhD, page 233

Although we think of caffeine in coffee as the "wake-me-up" chemical, chronic use of it may cause fatigue, headache, moodiness, and depression in some people. Because caffeine boosts energy through increasing the production of ATP, the basic unit of energy production in your body, one school of thought suggests that chronically stimulating this system may deplete it, sort of like overworking the soil in farmland. Recommendation: If you are a caffeine junkie (more than 3 cups of coffee a day) and can’t get through the day without your coffee fix, you may be promoting your fatigue with caffeine and need a rest period. Go slowly with your reduction to zero caffeine to avoid developing overwhelming sleepiness and a bad headache.
Doctors Complete Guide Vitamins Minerals by Mary D Eades MD, page 324

Caffeine can have a detrimental effect on blood sugar. When caffeine is ingested, the nervous system is stimulated. Adrenaline is released and, in turn, the liver begins to emit stored blood sugar. Insulin is then released, and blood sugar drops below normal—a common seizure trigger for people with epilepsy. Caffeine can also constrict blood vessels in the brain. It is important for people with epilepsy to know that caffeine can be an ingredient in medications, including some antihistamines and decongestants.
Disease Prevention And Treatment by Life Extension Foundation, page 739

For an optimal response to our plan, we recommend eliminating or sharply reducing your caffeine intake. Caffeine raises levels of adrenaline, causes overexcitation, increases stress, and impairs the relaxation response. It’s hard to be at peace when you’re revved up on caffeine.
Ultraprevention by Mark Hyman MD and Mark Liponis MD, page 241

Watch out for coffee. The caffeine in coffee can upset blood-sugar levels, leaving you fatigued and longing for a quick-pick-me-up snack. Limit coffee to two cups a day.
Food & Mood By Elizabeth Somer MA RD, page 57

Caffeine, in fact, is the most widely used cognitive-enhancement product in our society. Numerous tests have proved that, when used in moderate amounts, caffeine boosts concentration and alertness. Because it is a stimulant, it increases output of adrenaline, and can temporarily improve memory and mood.
Brain Longevity by Dharma Singh Khalsa M.D. with Cameron Stauth, page 266

Caffeine acts directly upon the central nervous system. It brings about an almost immediate sense of clearer thought and lessens fatigue. It also stimulates the release of stored sugar from the liver, which accounts for the "lift" coffee, cola, and chocolate give. But these benefits may be far outweighed by the side effects:
Vitamin Bible for the 21st Century by Earl Mindell, page 315

Caffeine doesn’t add energy to your system, it just burns up your reserves at a faster pace. You get a short-term boost at the expense of long-term jitters and fatigue.
The Unofficial Guide to Beating Stress by Pat Goudey, page 136

On the physical level, we need a steady source of energy to accomplish our goals. Nothing is more frustrating than to be motivated, to have a great plan, but no energy to carry it out. When I ask patients about their reasons for drinking coffee, the most common response is: "I need the energy." The irony is that caffeine is a major cause of fatigue. Depending on caffeine to get you through the day might work for a while, but in the long run it will make your dreams harder and harder to achieve.
Caffeine Blues By Stephen Cherniske MS, page 43

Avoid caffeine — it increases the stress hormones and adrenaline, which causes a spike in blood sugar.
Ultraprevention by Mark Hyman MD and Mark Liponis MD, page 306

The experts speak on caffeine, exhaustion and fatigue:

"Caffeine’s immediate effects on your body"

It doesn’t take a genius to see that there might be a downside to all of this neuron activity. In fact, uncontrolled neuron firing creates an emergency situation, which triggers the pituitary gland in the brain to secrete ACTH (adrenocorticotrophic hormone). ACTH tells the adrenal glands to pump out stress hormones—the next major side effect of caffeine.
Caffeine Blues By Stephen Cherniske MS, page 56

Within five minutes after you drink your morning coffee, the caffeine begins to stimulate your central nervous system, triggering the release of stress hormones in your body, causing a stress ("fight or flight" ) response. The stress hormones are useful if you need to prepare yourself to fight or flee a dangerous situation, but if you are simply sitting at your desk you may feel a short charge of alertness, quickly followed by feelings of agitation. Within the next hour or so, after the stress response dissipates, you will probably feel more tired and hungry. At these low-energy times, many people reach for another cup of coffee, or eat a snack that is often high in sugar to "pep up" and stay alert. However, both caffeine and sugar only give you temporary feelings of increased energy, which quickly dissipate. For some people, this cycle of low energy followed by an infusion of caffeine or food continues the entire day — leaving them feeling exhausted and unable to focus by 3:00 p.m. because they are drained from the ups and downs in energy their body endured throughout the day.
Active Wellness By Gayle Reichler MS RD CDN, page 12

Among other things, it stimulates the production of adrenaline, one of the hormones secreted by the adrenal glands to help us in extreme emergency situations. Our adrenals evolved to give our early ancestors the extra strength and alertness needed to escape a saber tooth tiger attack, but we don’t often need that much adrenaline these days. Like sugar, coffee constantly stimulates the production of adrenaline, putting excessive wear and tear on the adrenal glands. And let’s not forget that green tea and black tea contain caffeine, and even decaf still contains some caffeine. If you’re sensitive to caffeine it can keep you awake at night even if you haven’t had any since noon. If you’re suffering from insomnia, your best bet is to drink nonstimulating herbal teas such as chamomile or mint in the evening. If you need a boost in the afternoon, try a cup of ginseng tea.
Prescription Alternatives by Earl Mindell RPh PhD and Virginia Hopkins MA, page 388

Caffeine triggers a stress response that involves a surge in adrenal hormones and the classic fight-or-flight "emergency," affecting virtually every cell in the body.
Caffeine Blues By Stephen Cherniske MS, page 98

Everybody "knows" that caffeine makes you more alert and clearheaded. Think again. A cup of coffee gives you a wakeup jolt because it triggers a stress response. Your adrenal glands are prompted to kick out the same stress hormones that are released when you perceive an external threat or danger. Your muscles tense, your blood sugar elevates for extra energy, your pulse and respiration rates speed up, and your state of alertness increases so you’re ready to wrestle with or run from environmental dangers. You may be only sitting at your table or desk drinking a cup of coffee, but your body doesn’t know that. It’s preparing for action.
The Memory Solution by Dr Julian Whitaker, page 261

Caffeine increases the stimulating neurohormone, noradrenaline, and reduces the calming neurotransmitter, serotonin.
The Crazy Makers by Carol Simontacchi, page 191

Caffeine also stimulates the production of norepinephrine, another stress hormone that acts directly on the brain and nervous system. Epinephrine and norepinephrine are responsible for increased heart rate, increased blood pressure, and that "emergency" feeling. In fact, the emergency is quite real. caffeine can trigger a classic fight-or-flight stress reaction with all of the results listed in Illustration.
Caffeine Blues By Stephen Cherniske MS, page 57

I particularly recommend that you avoid caffeine. What caffeine actually does is set off a stress response. It stimulates your adrenal glands to make epinephrine and norepinephrine—the same stress hormones that are produced in response to any stressor. This sets the stress response in motion, causing tense muscles, elevated blood sugar, and increased pulse and respiration. You may feel mentally sharper because your brain is high on adrenaline. It’s ready to rumble. One cup of coffee for most people isn’t damaging. But as you may recall from our discussion of the three stages of the stress response, if stress hormones remain elevated, the body is thrown into a state of chronic stress. By sipping on coffee, tea, or caffeinated soda all day long, you are forcing your adrenal glands to continue to pump out stress hormones.
The Memory Solution by Dr Julian Whitaker, page 165