Extreme Fatigue: Individuals with ME/CFS experience profound fatigue that is not relieved by rest. This fatigue can be debilitating and significantly impacts daily activities.

Post-Exertional Malaise: After physical or mental exertion, individuals with ME/CFS often experience a worsening of symptoms that can last for days or even weeks. This post-exertional malaise is a hallmark feature of the illness.

Cognitive Impairment: Many individuals with ME/CFS experience cognitive difficulties, often referred to as "brain fog." This can manifest as problems with memory, concentration, and processing information.

Sleep Disturbances: Sleep disturbances are common in ME/CFS, with individuals often experiencing unrefreshing sleep, insomnia, or disrupted sleep patterns. These disturbances can further exacerbate symptoms.

Pain: Individuals with ME/CFS may experience various types of pain, including muscle pain, joint pain, and headaches. This pain can be widespread and contribute to the overall burden of the illness.