As I am sitting here, I have no energy.  It’s as if I was a balloon that was let go prematurely while it was being inflated…that’s how I feel right now.   My legs feel stuck to the ground, and my body feels oddly energetic, but that’s nothing more than the nerves trying to convince my muscles to hold me up at my desk.  So, because I am thinking about fatigue I figured I would give you the top 5 causes of fatigue, in the order that I believe are most common.

Lack of sleep

If one is looking for an answer to the cause of their fatigue, Occam’s Razor seems apropos, especially with an ambiguous complaint like “fatigue.”  The most common cause is poor sleep, and it’s no mystery that this insomnia is likely “secondary” to something else (see this article).  But not all poor sleep is created equal.  As we age our sleep patterns change.  Our physiological ability to obtain deeper levels of sleep wane while our physiological awakenings become more frequent.  This is frustrating for all involved! See the chart below.  The top chart shows young adults (less than 50 – I don’t make these rules up!) while the bottom chart shows the “elderly!”  For now, we will say this bottom chart represents a 60+ age range because those are the ages when I see these changes most.    You don’t have to be a doctor to see the differences, SPIKES (up), DEPTH (amount down), and WIDTH of DEPTH (“U-shaped” vs “V-shaped”).  To enter into a whole physiological discussion about sleep is way beyond the scope of this article, but understanding that normal aging processes affect sleep.

Our environment’s affect and our interpretation of it plays a huge roll as well on our sleep – we will call this stress/anxiety-related insomnia.  Our thoughts find a cycle of ruminations which can be quite torturous.  Let’s call this the “what ifs” cycle.  As in: 

What if I don’t have enough money to pay rent, I will have to tell my spouse, s/he will finally realize that s/he married a fraud, then we will lose the house, but where will my kids go to school?  Will they resent me?  how will we afford to move?  how will we come up with first and last month’s rent? Oh man, my car brakes are squeaking…how much is that going to cost me.  I still owe my cousin money.  Shit.   By this time, your eyes are wide open and you’ve turned over and over to try and convince your body that there’s a comfortable position, but to no avail.  So you get up and watch TV all night.  Shit, it’s only 2:30AM!  

Get it?  Try and seek help, whether it’s meditation, psychology, or your physician, start somewhere!  But don’t miss something that can be life threatening.  See below!


Obstructive Sleep apnea (OSA)
Look, it’s not only obese people that get OSA because people that have narrow airways can be affected as well.  See the Malampatti “Gene Simmons” reference chart below.  Apnea is a greek/latin word meaning “no breath.”   Most commonly peripheral (typical) sleep apnea is caused by either the soft palate collapsing during sleep or the mass of the neck causing airway obstruction, either way, you stop breathing (see video below).  This obstruction and lack of breath, causes the oxygen level to drop, essentially starving your tissues.  It’s no wonder that blood pressure and heart failure are two major outcomes of undiagnosed/untreated OSA.   If you are feeling un-rested after a presumed full night sleep and or suffer from dozing throughout the day, call your doctor to discuss the evaluation.  You can also click this link, fill out the form and bring it to your next doctor’s appointment:  ESS SCORE FOR SLEEP APNEA


This is anything that has to do with your chemicals or Blood.  From Diabetes to Dehydration to Anemia (low red blood cell count),  all of these can make you feel tired and fatigued throughout the day.  In other words, when our body isn’t working in tip top shape, we suffer.  We need certain things to function properly in our body to feed our muscles, brain, and heart so that we can feel rested.  Just like in OSA (above) when your muscles, brain, and heart don’t get enough rest (because they aren’t getting enough oxygen) they never get the chance to fully recover.  Anemia does that same thing.  Anemia has multiple causes but most of the physical effects are similar:  No energy.  Tired.  Rundown. Let’s break down where the energy comes from (simply): Each one of our red blood cells (RBCs) contain hemoglobin.  Hemoglobin has 4 arms.  Each arm holds an oxygen molecule.  The arms only work when there is iron – Iron is the glue that holds it all together!  Got it?  So when we are anemic, we can’t make these hemoglobin structures.  If the anemia is caused by lack of iron, there is no glue to hold it all together, so we start losing RBCs, thereby causing vital organs to starve and cause fatigue.  

INTERESTING FACT:  CO (carbon monoxide) kicks out Oxygen from hemoglobin and binds tightly.  The only way to dislodge CO from the hemoglobin is to give HIGH FLOW OXYGEN!  So check your Carbon Monoxide detector at home! 

Other major causes (quite a limited view) as we stated above would be dehydration (basically not getting enough fluids and electrolytes to vital organs) and other metabolic causes such as diabetes.  If you are feeling tired, please see your doctor.  There are so many things to consider to determine the cause, but you deserve to know, don’t you?

Simple enough right?  when you are not exercising and building muscle you are likely losing it.  Therefore, you are having to work even harder to do the same things when you had enough muscle.  That’s deconditioning in a nutshell.   There is also psychological deconditioning  (or maybe I’ll call it psychological atrophy) –  Have you ever just found yourself binge watching TV, so much so, that any activity other than lifting the twinkie and placing it in your mouth is simply laughable?   Now imagine how that behavior will effect you energetically if carried on for months at a time.  This behavior also helps us define the old paradox that it takes energy to make energy.   We’ve all been there probably, I haven’t worked out in weeks, I’m too tired to exercise so screw it, I’ll just stay here.  Sound familiar?

Not all depression is depression.  Not all feelings of depression are clinical.  You are human, so accept that depressive feelings are a part of this life.  The part of depression that makes you tired could be related to the psychological deconditioning as noted above, or avolition and anhedonia:

Avolition – lack of interest or motivation towards goal-oriented behavior

Anhedonia – One’s inability to feel pleasure. 

In no uncertain terms, anyone can see that if anyone suffers from depression or depressive feeling which have one or both of these symptoms fatigue would ensue.   If you suffer from depressive feelings or depression, seek help. You are only alone if you make yourself alone.  There are plent of people to help you.  Remember this, it’s not weak to ask for help.  It’s weak to pretend you don’t need it.  Please reach out…even here.

Undiagnosed/Occult infection
It’s not Lyme disease.  Just saying.  I mean it can be, but let’s face it, unless you are camping in the Rockies, and yanked a tick out from your skin then you probably don’t have Lyme.   HIV, cellulitis (skin infection), Herpes (chicken pox, shingles or genital), Cancer, common flu or cold all can cause fatigue and all can be easily overlooked or undiagnosed (well at least some of them). 

The take home message here is, if you have fatigue, that can’t be explained by simple, reversible changes, reach out to your doctor and have yourself checked out.  Especially if you think you’re too tired to make the call!


Dr. Mike

About the author

I am a Board Certified Family Practice Physician (MD) that has a passion for the proper treatment of patients. We are more than just our physical beings. We are complex and the current medical climate is failing both patients and physicians. As a new author, I feel passionately about letting everyone know how the system is failing us, moreover, how to overcome these barriers!
Michael Lewis, MD
I am board certified in family medicine and passionate about caring for the whole patient: mind, body, spirit. I am married to a wonderful woman Jenniffer, who is a clinical psychologist and works right here in Willow Medical Center. I have a 7-year-old daughter, Bailey who is the light of my life. I am a soul searcher for myself and others. I also love to help men reach their potential as a conscious male. I am also a musician/guitarist. I have found that nurturing this part of my brain helps me think out of the proverbial box and provide better medicine.