Why Am I So Tired All the Time? Common Causes and What Helps

If you feel tired all the time, the most common reasons are everyday ones: not enough sleep, poor quality sleep from late caffeine, alcohol or screens, heavy meals, too little water or movement, and not getting enough iron or vitamin B12. (CDC; NIH ODS; NIH ODS) Most of these you can check and change yourself, and this guide shows how. Tiredness that does not lift with better habits, or that comes with other symptoms, is a reason to see a doctor (MedlinePlus).

It is educational, not medical advice.

Key Takeaways

• Sleep first: adults need 7 or more hours of sleep, at the same bedtime and wake time every day (CDC).
• Sleep quality counts too: caffeine even 6 hours before bed disturbed sleep (Drake et al., 2013), and alcohol disrupts the second half of the night (Ebrahim et al., 2013).
• Check iron and B12: not getting enough of either can leave you tired and weak; women with heavy periods, vegetarians, vegans and older adults are among those more likely to fall short (NIH ODS; NIH ODS).
• Drink and move: mild dehydration of about 1.4% of body weight worsened fatigue and mood in young women (Armstrong et al., 2012), and regular exercise increased feelings of energy across studies (Puetz et al., 2006).
• Know when to get help: fatigue with fever, weight loss you did not plan, or night sweats needs a doctor's visit (MedlinePlus).

Why Am I So Tired All the Time? 8 Common Causes

Cause	What you may notice	What to try
Not enough sleep	Fewer than 7 hours most nights	A fixed bedtime and wake time (CDC)
Late caffeine	Coffee or energy drinks after mid-afternoon	Last caffeine 6 hours before bed (Drake et al., 2013)
Alcohol in the evening	Waking in the second half of the night	Skip the nightcap (Ebrahim et al., 2013)
Screens in bed	Taking longer to fall asleep	Devices off 30 minutes before bed (CDC)
Heavy meals	Sluggish after lunch or dinner	Lighter meals, especially before bed (CDC)
Too little water	Low energy, harder to concentrate, headache	Drink through the day (Armstrong et al., 2012)
Too little movement	Feeling flat, little exercise most weeks	Regular exercise (Puetz et al., 2006)
Not enough iron or B12	Tired and weak, especially with a diet low in animal foods or heavy periods	Food first; ask your doctor about a blood test (NIH ODS; NIH ODS)

1. You Are Not Getting Enough Sleep

The CDC recommends 7 or more hours of sleep for adults aged 18 to 60, 7 to 9 hours from 61 to 64, and 7 to 8 hours from 65 (CDC). If your alarm cuts that short on most days, tiredness is the expected result. Going to bed and getting up at the same time every day is the first habit the CDC lists (CDC). Our guide to how to sleep better covers the rest.

2. Your Sleep Is Lighter or More Broken Than You Think

You can be in bed for 8 hours and still wake up tired if the sleep itself is broken. Three common culprits:

• Caffeine: 400 mg of caffeine taken at bedtime, 3 hours before bed or 6 hours before bed all disturbed sleep compared with placebo (Drake et al., 2013).
• Alcohol: it helps you fall asleep faster but disrupts the second half of the night and reduces REM sleep at moderate and high doses (Ebrahim et al., 2013).
• Screens: reading on a light-emitting e-reader before bed meant taking longer to fall asleep and feeling less alert the next morning than reading a printed book (Chang et al., 2015).

If mornings are the hardest part, our guide to how to wake up when you are tired has practical steps.

3. Big Meals Leave You Sluggish

Feeling sleepy an hour or two after a large meal is common. The CDC advises avoiding large meals before bedtime (CDC), and our guide to why you feel tired after eating explains what drives the after-meal slump and how to plan meals around it.

4. You Are Not Getting Enough Iron or Vitamin B12

When iron runs low, the NIH lists weakness, tiredness and lack of energy among the signs (NIH ODS). Low vitamin B12 can also make you feel tired or weak (NIH ODS).

• Iron: adults aged 19 to 50 need 8 mg a day for men and 18 mg for women. Women with heavy periods, pregnant women and frequent blood donors are among those more likely to fall short (NIH ODS).
• Vitamin B12: adults need 2.4 mcg a day. Older adults, and people who eat little or no animal foods such as vegetarians and vegans, are more likely to have trouble getting enough (NIH ODS). Our guide to vitamin B12 foods lists the best sources.

A blood test is the way to know. Ask your doctor before taking iron supplements: iron products must be kept away from children, as accidental overdose is a leading cause of fatal poisoning in children under 6 (NIH ODS).

5. You Are Mildly Dehydrated

In a placebo-controlled study of 25 healthy young women, losing about 1.4% of body weight in water through exercise worsened vigor, fatigue and mood, and made tasks feel harder, with lower concentration and more headaches (Armstrong et al., 2012). Keep water nearby and drink through the day, more when you exercise or it is hot.

6. You Are Not Moving Enough

It sounds backwards, but moving more can leave you feeling less tired. A review of exercise studies found that regular exercise increased feelings of energy and lessened feelings of fatigue compared with control groups (Puetz et al., 2006). The CDC lists regular exercise among habits that improve sleep as well (CDC).

7. Stress and Mental Load

Long stretches of stress can feel like constant tiredness. Our guide to fatigue vs burnout explains how to tell the two apart and what helps with each.

8. Something Else Is Going On

Many health issues and some medicines can cause fatigue (MedlinePlus). If the habits above do not help within a few weeks, see the doctor section below.

What Helps When You Are Always Tired

1. Protect 7 or more hours of sleep with a fixed bedtime and wake time (CDC).
2. Cut caffeine 6 hours before bed (Drake et al., 2013) and skip alcohol in the evening (Ebrahim et al., 2013).
3. Eat regular, balanced meals with good sources of iron and B12 (NIH ODS; NIH ODS).
4. Drink water through the day (Armstrong et al., 2012).
5. Move most days (Puetz et al., 2006). Our guide to how to get more energy has more daily habits, and vitamins for energy covers which nutrients matter.

Where Our Products Fit

Our Methyl B-12 Nasal Spray provides 408 mcg of vitamin B12 as methylcobalamin per two-spray serving, used once a day; many people take it in the morning. It is one way to get B12 if your diet is low in animal foods. The Energy Stack pairs it with NAD+ Nasal Spray and Forage in one daily energy routine. Learn more in our vitamin B12 benefits guide, on our methyl B12 ingredient page and in our non-stimulant energy and focus hub. Talk to your doctor before starting a new product if you are pregnant, breastfeeding or take medication.

When to See a Doctor

Book an appointment if you have tiredness or weakness you cannot explain, especially with fever, weight loss you did not plan, or regular sweats; if you feel cold all the time with dry skin, constipation or weight gain; if you wake many times in the night or snore loudly; if you have frequent headaches; if you take medicines that may cause drowsiness; or if you feel sad or low (MedlinePlus). Possible causes your doctor may check include anemia, an underactive or overactive thyroid, sleep apnea, depression and diabetes (MedlinePlus).

Safety note: contact a doctor right away for confusion or dizziness, blurred vision, little or no urine, or recent swelling and weight gain (MedlinePlus). If you have thoughts of harming yourself, call or text 988 in the US.

Frequently Asked Questions

Why am I so tired all the time?

The most common reasons are too little sleep, broken sleep from late caffeine, alcohol or screens, heavy meals, too little water or movement, and low iron or B12 intake (CDC; NIH ODS; NIH ODS). If better habits do not help, see a doctor (MedlinePlus).

Why do I feel tired after 8 hours of sleep?

Time in bed is not the same as good sleep. Caffeine up to 6 hours before bed (Drake et al., 2013), evening alcohol (Ebrahim et al., 2013) and screens (Chang et al., 2015) can all leave you less rested. Waking many times in the night is a reason to see a doctor (MedlinePlus).

Why am I so tired when I wake up?

Often it is a short or broken night, or a bedtime that changes from day to day (CDC). Reading on a light-emitting screen before bed reduced next-morning alertness in one study (Chang et al., 2015).

Why am I always tired as a woman?

The same causes apply, plus iron: women aged 19 to 50 need 18 mg a day, and women with heavy periods or who are pregnant are more likely to fall short (NIH ODS).

Can low B12 make you tired?

Yes. Low vitamin B12 can make you feel tired or weak, and older adults, vegetarians and vegans are more likely to have trouble getting enough (NIH ODS).

Can dehydration make you tired?

Yes. Losing about 1.4% of body weight in water worsened fatigue, vigor and mood in healthy young women (Armstrong et al., 2012).

Does exercise help with tiredness?

Across studies, regular exercise increased feelings of energy and lessened feelings of fatigue compared with control groups (Puetz et al., 2006).

When should I see a doctor about being tired?

When tiredness does not improve with better habits, or comes with fever, weight loss you did not plan, night sweats or low mood. Get help right away for confusion, dizziness or blurred vision (MedlinePlus).

Sources

1. Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013. PubMed 24235903
2. Ebrahim IO, Shapiro CM, Williams AJ, Fenwick PB. Alcohol and sleep I: effects on normal sleep. Alcohol Clin Exp Res. 2013. PubMed 23347102
3. Chang AM, Aeschbach D, Duffy JF, Czeisler CA. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proc Natl Acad Sci U S A. 2015. PubMed 25535358
4. Armstrong LE, Ganio MS, Casa DJ, et al. Mild dehydration affects mood in healthy young women. J Nutr. 2012. PubMed 22190027
5. Puetz TW, O'Connor PJ, Dishman RK. Effects of chronic exercise on feelings of energy and fatigue: a quantitative synthesis. Psychol Bull. 2006. PubMed 17073524
6. Centers for Disease Control and Prevention. About Sleep. CDC
7. NIH Office of Dietary Supplements. Vitamin B12: Fact Sheet for Consumers. NIH ODS
8. NIH Office of Dietary Supplements. Iron: Fact Sheet for Consumers. NIH ODS
9. MedlinePlus. Fatigue (reviewed May 2025). MedlinePlus

Our products are not intended to diagnose, treat, cure or prevent any disease. This article is for education only and is not medical advice.