Feeling Drained? Here’s What’s Actually Going On and How to Fix It

Tips and insights from Raelene Brooks, Ph.D., RN, Dean, College of Nursing, University of Phoenix

Low energy is one of the most common complaints people bring to their doctors, and one of the most misunderstood. It’s easy to write off fatigue as the price of a packed schedule or a string of rough nights. But according to Raelene Brooks, Ph.D., RN, Dean of the College of Nursing at the University of Phoenix, the truth is more nuanced than that. “Energy levels are shaped by a complex interplay of environmental conditions, lifestyle habits, and underlying health factors,” she explains. The good news? Once you understand what’s behind the fatigue, there’s a lot you can actually do about it, and the results tend to come faster than most people expect.

What’s Actually Draining Your Energy?

Dr. Brooks points to three broad categories she sees again and again in clinical practice: problems with oxygen delivery, hormonal and metabolic disruptions, and environmental influences.

Oxygen Delivery

The body’s energy is fundamentally tied to how well oxygen reaches your tissues and organs. Several everyday conditions can quietly undermine this process.

• Dehydration: When you lose water, especially in hot or dry conditions, your red blood cells begin to shrink. That matters because these cells are responsible for carrying oxygen throughout your body. A shrunken red blood cell simply can’t carry a full load, which means less oxygen reaches your tissues. The result shows up as fatigue, irritability, and restlessness.
• High Blood Sugar (Hyperglycemia): Excess glucose in the bloodstream increases blood viscosity and can physically damage red blood cells, further reducing their ability to deliver oxygen where it’s needed.
• Congestive Heart Failure: When the heart can’t pump blood efficiently, oxygen delivery is compromised at the source. This kind of fatigue tends to be persistent and gets worse with activity.
• Chronic Respiratory Issues: Conditions that impair lung function limit how much oxygen enters the bloodstream in the first place, leaving the whole body running on less.
• Sleep Apnea: During airway obstructions, the body can’t properly inhale oxygen or exhale carbon dioxide. Elevated CO2 levels are directly tied to sleepiness, brain fog, and fatigue, even after a full night in bed.

Hormonal and Metabolic Factors

• Hypothyroidism: The thyroid gland regulates your metabolism and energy production. When it’s underactive, everything slows, and persistent fatigue is often the very first sign.
• Kidney Disease: The kidneys produce a hormone that helps regenerate red blood cells. When kidney function declines, red blood cell production can drop too, reducing the body’s overall oxygen-carrying capacity.

Environmental Influences

• Reduced Sunlight: Sunlight triggers serotonin production in the brain, a neurotransmitter that influences energy, mood, focus, and calmness. As daylight hours shorten in fall and winter, serotonin levels can dip noticeably, bringing on that familiar seasonal sluggishness.

Four Things You Can Do Right Now

Dr. Brooks is clear that the same factors draining your energy can often be addressed proactively. The key, she emphasizes, is consistency. “The body is remarkably adaptable, but it needs sustained input before it recalibrates.” Here are four evidence-based strategies she recommends:

• Stay Hydrated: Proper hydration keeps red blood cells at their optimal size and shape, maximizing their capacity to carry oxygen. Sip water steadily throughout the day rather than trying to catch up with large amounts at once. If you’re active or in a warm environment, your needs go up accordingly.
• Move Your Body: Exercise raises your heart rate and gets blood and oxygen, circulating more efficiently. Even a brisk 20-minute walk can make a meaningful difference over time. It feels counterintuitive to move when you’re already exhausted, but the payoff is real.
• Practice Deep Breathing: Slow, full inhalations followed by complete exhalations increase your oxygen intake and help clear carbon dioxide from your system. It’s one of the simplest, most underused tools for sharpening alertness and cutting through that heavy, cloudy fatigue feeling.
• Get More Sunlight: Beyond boosting serotonin, sunlight supports bone health, helps regulate blood pressure, and triggers your body’s production of vitamin D, low levels of which have been linked to both obesity and chronic fatigue. Even 15 to 20 minutes of outdoor exposure most days can yield real, measurable benefits.

When to See a Doctor

Lifestyle changes go a long way, but Dr. Brooks is careful to note that chronic fatigue, especially when it persists despite real effort, can be the body’s way of flagging something more serious. “Fatigue is one of the most common ways the body signals a systemic or metabolic issue,” she says. “It should never be routinely dismissed.”

Seek prompt medical attention if your fatigue is accompanied by shortness of breath or pain in the neck, chest, back, or abdomen, these combinations can point to serious cardiovascular or pulmonary conditions.

People with preexisting conditions, high blood pressure, diabetes, obesity, or high cholesterol should pay especially close attention to changes in their energy levels. In these cases, fatigue may be an early sign that something is worsening or poorly controlled. When in doubt, a conversation with your healthcare provider is always the right call.

“Energy is not simply a matter of willpower or sleep,” Dr. Brooks reminds us. “It’s a product of how well the body is oxygenated, hydrated, nourished, and supported by its environment.” Start with one or two of these strategies, build the habit, and let your body respond. It will.

Raelene Brooks, Ph.D., RN  |  Dean, College of Nursing, University of Phoenix

Dr. Brooks leads nursing education initiatives at the University of Phoenix, focusing on health equity, clinical excellence, and evidence-based practice.