Knowra Lethargy Lethargy Lethargy is abnormal drowsiness, sluggishness, or reduced energy and responsiveness. It can arise from ordinary sleep loss, illness, medication, or serious disruption of brain function.
Arousal : A state of wakefulness and responsiveness governed by brain systems that regulate attention and consciousness. Reduced arousal can make lethargy progress from sluggishness to difficulty staying awake.
Mental status examination : A structured assessment of a person’s appearance, behavior, cognition, mood, and level of consciousness. It helps clinicians describe responsiveness and identify changes accompanying lethargy.
Fatigue : A subjective sense of physical or mental exhaustion that may not improve fully with rest. Fatigue describes depleted energy, whereas lethargy emphasizes drowsiness or reduced responsiveness.
Level of consciousness : The degree of wakefulness and awareness of oneself and the surrounding environment. Lethargy describes reduced alertness along this broader clinical continuum.
Sleep deprivation : A condition caused by obtaining less sleep than the body needs. Insufficient sleep commonly impairs alertness and produces daytime lethargy.
Glasgow Coma Scale : A clinical scale that scores eye, verbal, and motor responses to assess impaired consciousness. Its response scores help quantify reduced responsiveness when lethargy is severe.
Hypersomnia : Excessive sleepiness or unusually prolonged sleep that interferes with waking life. Hypersomnia concerns excessive sleep propensity; lethargy is a broader description of sluggishness and reduced response.
Delirium : An acute, fluctuating disturbance of attention and awareness, often accompanied by confused thinking. Lethargy can accompany delirium, but delirium specifically involves impaired attention and awareness.
Circadian rhythm : An internal cycle of roughly 24 hours that coordinates biological processes, including sleep and wakefulness. Circadian misalignment can cause drowsiness when the body is expected to be alert.
Differential diagnosis : The process of distinguishing among conditions that could explain a person’s signs and symptoms. Many unrelated illnesses and exposures can produce lethargy, so its cause must be assessed.
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