inferior frontal cortex (IFC) plays a specialized role in response inhibition. It seems that this region plays a key role in the integration of bottom-up response-related information and facilitates goal-directed behavior. While these areas of the brain are known to be involved in DAF, their specific molecular mechanisms in the perpetuation of DAF symptoms are not yet known. Diagnosis Differential diagnosis The concept of stress is used in many situations that would be described as mental fatigue, but the two concepts are distinctly different. Stress involves preparation for an anticipated event that has been evaluated as being threatening or harmful. Though mental fatigue may well result from stressful circumstances, it also arises out of hard work on a project one enjoys. In such cases, there is no anticipation of threat or harm present but still the result is fatigue. Characteristic of mental fatigue is difficulty focusing. For a mentally fatigued person, paying attention to something uninteresting is burdensome, even though focusing on something of great interest poses no particular challenge. Hence, there are two types of attention, distinguished in terms of the effort involved in their use and their changes in attentional shift: Involuntary attention refers to attention that requires no effort at all, as when something exciting or interesting happens. Voluntary attention, or directed attention, refers to attention that requires a great deal of effort, as when something is monotonous or boring. Treatment There are measures that can be taken in order to reduce the impact of DAF. These include reducing the number of distractions present in one's external environment, trying to clear one's mind of any internal distractions and taking short breaks during prolonged periods of focus. Directed attention fatigue can be reduced by getting a sufficient amount of sleep each night, because inhibitory attention chemicals are replenished during sleep. An aesthetic environment may also serve a restorative function in fostering recovery from mental fatigue. Research has shown that restorative experiences, such as clearing one's head and reflecting on one's life and priorities, may help combat Directed Attention Fatigue. As investigated by attention restoration theory, natural environments, such as forests, mountain landscapes or beaches, appear to be particularly effective for restoring attention, perhaps because they contain a vast amount of diverse, relatively weak stimuli, thus inciting the mind to wander freely while relaxing its strict focus. Research Ongoing research is examining ways in which the incidence of DAF