Vireysjaksoja

Vireysjaksoja is a Finnish term used in psychology, sleep medicine, and neurorehabilitation to describe episodes of increased arousal or alertness. The word combines vireys (alertness or vigor) with jakso (period or phase). In Finnish research, vireysjaksoja refer to transient states during which an individual becomes more cognitively and physiologically activated, in contrast to periods of fatigue or reduced responsiveness.

The exact definition and measurement can vary across studies. In some contexts, a vireysjaksoja is identified by observable changes in behavior (improved attention, faster reaction times), physiological indicators (increased heart rate, skin conductance), or specific neurophysiological patterns. The concept is used to understand fluctuations in alertness during wakefulness, fatigue management, sleep deprivation experiments, rehabilitation after brain injury, and attentional disorders such as ADHD.

Because the term is primarily used in Finnish-language sources, there is no universally accepted international definition, and translations depend on context (for example, arousal episodes or periods of increased vigilance). Researchers emphasize that vireysjaksoja are situational and can vary in duration from a few seconds to several minutes.

See also: arousal, wakefulness, sleep stages, fatigue.