Persistent fatigue is often caused by treatable conditions, including depression, alcohol abuse, Lyme disease, or anemia. In fact, 18% of patients who were referred to a Centers for Disease Control and Prevention surveillance study for chronic fatigue syndrome were later disqualified from the study after being diagnosed with a disease known to cause fatigue. All of these patients had first been screened by their primary care provider, who failed to make a diagnosis. But a large number of nurses with short-term or intermittent fatigue really suffer from sleep deprivation, sometimes made worse by caffeine or alcohol.

Sleep Deprivation

It’s impossible to predict how much sleep each person needs: eight hours may be too little for one person, but too much for another. Although the amount of sleep we get changes little with age, the quality of sleep does change. After age 50 years for men and 60 for women, the amount of deep sleep diminishes, and sudden noises are more likely to cause waking. Brief awakenings, only seconds long, become more common and frequent among the elderly.

Although everyone is built to sleep at night, many nurses have little choice except to sleep during the day. According to the National Sample Survey of Registered Nurses, 60% of nurses work in hospitals and another 8% work in nursing homes or extended-care facilities, where they may be required to work schedules that interfere with their usual sleep patterns.

Scheduling patterns may make matters worse. Studies show that shiftworkers sleep better and are more alert at work when they rotate forward, moving around the clock from days, to afternoons, to midnights. Short rotations are more difficult to adjust to than longer rotations, and longer shifts are more fatiguing than shorter shifts. It usually takes two weeks to adjust sleep to a new shift, but nurses who try to sleep during the night on their days off may never adjust.

Younger nurses adapt better to rotating shifts, and some nurses who once tolerated off-shifts begin to suffer from insomnia in their 40s or 50s. These changes occur as our internal clocks speed up with age. During adolescence and early adulthood, our internal clocks think the day is longer than 24 hours. As a result, it’s very difficult to fall asleep early or awaken early. During our late 20s and 30s, our internal clocks speed to about 24 hours and sleeping and waking go on schedule. Starting in middle age, our internal clocks may be shorter than 24 hours and waking up on time is easy. The internal clocks for the elderly speed further, which accounts for early bedtimes and early morning awakenings.

How Much Coffee is Too Much?

Caffeine is the most commonly used drug to self-medicate fatigue. Researchers have confirmed that 200 mg of caffeine, equal to two or three cups of coffee, improves performance of monotonous tasks, such as long-distance driving. The improved performance continued during the third and fourth hours of the experiment. But caffeine is most effective when it’s used infrequently, following two or three days of abstinence. Tolerance to caffeine quickly develops and larger doses are needed to achieve the same effect.

Regular coffee use leads to physical dependence and a recognizable withdrawal syndrome, including headache, sleepiness, and lethargy. Withdrawal symptoms begin 12 to 16 hours after cessation of caffeine, peak at 24 to 48 hours, and continue for about a week. Regular caffeine use is thought to increase the number or activity of receptors for the neurotransmitter adenosine. During withdrawal the receptors are hypersensitive. For many people, a morning cup of coffee leads to increased alertness because it treats withdrawal symptoms.

Some nurses use caffeine as a substitute for sleep, increasing the dose as they become progressively more tired. For many people caffeine interferes with sleep and worsens fatigue. To treat the fatigue, they increase the dose of caffeine, which further interferes with sleep. Once a higher plateau of caffeine use is reached, a higher dose of caffeine is needed to fight withdrawal symptoms.

Forget the Nightcap

Nurses can also disrupt their sleep with a nightcap. Although alcohol seems to speed the onset of sleep, it reduces its length and quality. Nurses who drink a nightcap are far more likely to awaken after a few hours and be unable to fall back to sleep. They have also altered their neurotransmitters in a way that disrupts their cycles of deep and rapid-eye-movement sleep, so that they feel less rested. As these nurses develop a tolerance to alcohol, it takes a greater number of drinks to feel drowsy, further degrading sleep quality. Alcohol also increases the likelihood of snoring and awakenings related to sleep apnea. Alcohol’s effects are most pronounced during the first three hours following a drink, so it should be avoided by night nurses unless they plan to drink at 9:00 AM and go to sleep after noon.

Instead of taking sleep for granted, nurses who work shifts need to guard and nurture their sleep with delicate precision. The consequences of fatigue and poor concentration after a bad night’s sleep may be poor clinical judgment and unintentional harm.

Jeffrey Zurlinden, RN, MS, is a contributing editor for Nursing Spectrum.