More than one-third of adults report feeling tired or fatigued most days. While occasional tiredness is normal, persistent fatigue is different—it’s a draining lack of energy that makes it difficult to get through the day. Fatigue often becomes more common as we age, but that doesn’t mean you have to accept it as part of life.
By understanding the causes of fatigue and taking simple steps to improve your energy, you can start to feel more alert, focused and refreshed.
What Is Fatigue?
Fatigue isn’t just the sleepiness you feel at the end of a busy day. It’s a constant state of weariness that can be physical, mental or both. People with fatigue often describe feeling completely drained, even after getting a full night’s rest.
This exhaustion can make everyday tasks feel overwhelming and may bring on “brain fog,” making it difficult to think clearly or concentrate. While fatigue can affect anyone, it tends to be more common in middle age and beyond due to natural changes in the body and lifestyle.
What Are the Signs of Fatigue?
Fatigue is more than just being tired. Common signs include:
- Trouble concentrating or making decisions
- Feeling unmotivated or lethargic
- Daytime sleepiness or dozing off during quiet activities
- Aching or sore muscles
- Mood changes such as irritability or anxiety
- Frequent headaches or dizziness
Why Am I So Tired? Common Causes of Fatigue
If you often wonder, “Why am I so tired even after sleeping?” you’re not alone. Fatigue can have many different causes—sometimes a combination of them.
1. Natural Aging and Energy Levels
As we age, our bodies go through normal changes. Muscle mass decreases, metabolism slows and hormones shift. Sleep patterns also change, making it harder to get deep, restorative rest. Together, these changes can lower your energy reserves.
2. Poor Sleep Quality
You may spend eight hours in bed, but that doesn’t always mean you’re getting quality sleep. Sleep disorders are a leading cause of daytime fatigue. Conditions like sleep apnea or insomnia disrupt the sleep cycle and prevent your body from fully recharging.
3. Lifestyle Factors
Daily habits play a big role in how energized or drained you feel:
- Diet: High-sugar and processed foods can cause energy spikes followed by crashes.
- Hydration: Even mild dehydration can leave you feeling sluggish.
- Exercise: A sedentary lifestyle can worsen fatigue, while regular movement helps boost stamina.
- Stress: Chronic stress floods the body with stress hormones, leaving you mentally and physically exhausted.
4. Underlying Medical Conditions
Sometimes, fatigue signals an underlying health issue. Common conditions linked to fatigue generally include:
- Thyroid disorders (especially hypothyroidism)
- Anemia (low iron levels)
- Diabetes
- Heart disease
- Chronic fatigue syndrome
- Vitamin D deficiency
- Lyme disease
5. Medications
Certain prescription and over-the-counter medications can cause fatigue as a side effect. These may include some blood pressure drugs, antidepressants, antihistamines and pain relievers.
If your tiredness started after beginning a new medication, talk to your doctor.
How to Fight Fatigue and Improve Energy
The good news is that fatigue can often be managed with small, consistent changes to your daily routine.
Prioritize Quality Sleep
Prioritizing sleep and creating a consistent nighttime routine helps your body recharge, making it easier to maintain steady energy throughout the day. True rest comes from deep, restorative sleep. Without it, even a full night in bed can leave you feeling drained and unrefreshed.
- Stick to a routine: Go to bed and wake up at the same time every day. Remember to plan for 7-9 hours of sleep nightly.
- Wind down before bed: Turn off screens 30-60 minutes before bed. Read or take a warm bath/shower to relax your body for sleep.
- Create a sleep-friendly environment: Keep your bedroom dark, cool and quiet.
Stay Physically Active
It may seem counterintuitive, but exercise actually boosts energy. Start with light activities, such as a brisk 30-minute walk. Then build up your exercise routine as you become more comfortable.
Regular movement improves circulation, strengthens muscles and increases endorphins—your body’s natural energy boosters.
Eat for Steady Energy
What and when you eat can have a big impact on your energy levels throughout the day. Choosing balanced foods helps prevent energy crashes and supports more restorative sleep at night.
- Prioritize protein and fiber: Pair lean proteins (chicken, fish, beans, eggs) with high-fiber foods (vegetables, whole grains) to keep blood sugar stable.
- Limit added sugars: Sugary snacks and drinks cause a quick spike in energy followed by a crash, leaving you feeling even more fatigued.
- Stay hydrated: Even mild dehydration can contribute to tiredness. Aim to drink water consistently throughout the day.
- Listen to your body’s cues: Eat when you’re hungry and stop when you’re satisfied. Honoring your natural hunger rhythms helps avoid both energy dips from under-eating and sluggishness from overeating.
Manage Stress
Chronic stress can be draining, but healthy coping strategies can help.
- Practice mindfulness, meditation or deep breathing.
- Set boundaries to avoid overcommitting.
- Connect with supportive friends or loved ones.
- Find outlets or hobbies that bring you joy.
Talk to a Doctor
If your fatigue doesn’t improve with lifestyle changes, it’s important to see a healthcare provider. They can check for underlying medical conditions and nutrient deficiencies, or adjust medications that may be contributing to your tiredness.
When to Seek Help
Persistent fatigue isn’t something you need to live with. If ongoing tiredness is interfering with your quality of life, a sleep specialist can help uncover the cause and create a personalized treatment plan for you.
At Stony Brook Sleep Disorders Center, specialists are dedicated to diagnosing and treating sleep disorders using state-of-the-art technology and personalized care plans. Recognizing the unique needs of each patient, they provide targeted treatments to improve sleep quality and address conditions such as sleep apnea, insomnia and more.
