7 Reasons You’re Tired after Surgery

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Postsurgical fatigue introduction

Patients often question why they are so tired after surgery. Many patients think that because they have been “put to sleep with anesthesia” that they should be refreshed and have more energy as they recover from their surgery. However, the tired feeling (fatigue) after surgery is the usual situation for most patients and there are some reasons for this outcome.

Sleep deficit

Some reasons begin even before surgery. For example, many patients have anxiety about undergoing any type of surgery and find it difficult to sleep, especially right before the date of surgery. Consequently, many patients have a sleep deficit even before they undergo surgery. This sleep deficit must be made up so the body triggers "sleepiness or fatigue" as a way to pay off this deficit. Anesthetics do not make up for this sleep deficit, so the body still has it after surgery.

Anemia and blood loss

One of the consequences of low red blood count (anemia) is that person can have fatigue. If the patient has a history of anemia before surgery they are already primed to feel tired and sleepy after surgery. Even patients who are not anemic before surgery may become anemic during or after surgery because of blood loss during and after the procedure. In addition to feeling fatigued and/or sleepy, the patient who has lost blood may have a tendency to feel weak and/or dizzy when they try to sit up or stand up. Also, they may feel fatigued because they work harder to breathe since the anemia has decreased oxygen carrying capacity due to fewer red blood cells available to carry oxygen to the body's tissues.

Medically Reviewed by a Doctor on 11/23/2015

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