Sleep: Understanding the Basics
Medical Author:
Michael B Russo, MD
Coauthor:
Shehnaz Shaikh, MD
Medical Editor:
Anthony M Murro, MD
Medical Editor:
Francisco Talavera, PharmD, PhD
Medical Editor:
Carmel Armon, MD, MHS, MSc
Basics of Sleep IntroductionSleep is defined as a state of unconsciousness from which a person can be aroused. In this state, the brain is relatively more responsive to internal stimuli than external stimuli. Sleep should be distinguished from coma. Coma is an unconscious state from which a person cannot be aroused. Sleep is essential for the normal, healthy functioning of the human body. It is a complicated physiological phenomenon that scientists do not fully understand. Historically, sleep was thought to be a passive state. However, sleep is now known to be a dynamic process, and our brains are active during sleep. Sleep affects our physical and mental health, and is essential for the normal functioning of all the systems of our body, including the immune system. The effect of sleep on the immune system affects one’s ability to fight disease and endure sickness. States of brain activity during sleep and wakefulness result from different activating and inhibiting forces that are generated within the brain. Neurotransmitters (chemicals involved in nerve signaling) control whether one is asleep or awake by acting on nerve cells (neurons) in different parts of the brain. Neurons located in the brainstem actively cause sleep by inhibiting other parts of the brain that keep a person awake.Viewer Comments & ReviewsSleep - Problems ExperiencedThe eMedicineHealth physician editors ask:What sleep problems have you experienced? Sleep Apnea - CausesThe eMedicineHealth physician editors ask:What was the treatment for your sleep problems? |
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Chronic Fatigue Syndrome Overview
Chronic fatigue syndrome (also called CFS) is a disorder without a known cause, although CFS may be related to a previous infection. CFS is a state of chronic fatigue that exists without other explanation for six months or more and is accompanied by cognitive difficulties (problems with short-term memory or concentration). You may have CFS if you meet the following criteria:
- if you have severe chronic fatigue for six months or longer and all other known conditions that could cause fatigue have been excluded by your health-care provider, or
- if you simultaneously have four or more of the following symptoms: significant problems with short-term memory or concentration, sore throat, tender lymph nodes, muscle pain, pain in several joints without swelling or redness, headaches that are different in pattern or severity from previous headaches, feeling tired and unrefreshed even after sleeping, and extreme tiredness ...
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