קהלת, פרק ח׳, פסוק ט״ז

The relentless pursuit of understanding the world and the mysteries of human existence exacts a heavy toll, often robbing a person of inner peace. Reflecting on past conclusions [רש״י], a close observation of human behavior reveals a troubling reality: the righteous sometimes suffer the fate of the wicked. This profound realization plunges the mind into deep, consuming thought [אבן עזרא, מצודת דוד, ביאור שטיינזלץ]. Because God graced the author with extraordinary wisdom, he fully devoted himself to unraveling this mystery, examining it to its very core [תעלומות חכמה].

This intense state of mind leads to a complete loss of sleep, a condition understood in several distinct ways. The primary approach among commentators views this exhaustion as the ultimate price of wisdom. A person who completely dedicates himself to investigating the world finds no rest, as an overwhelming flood of thoughts keeps him awake day and night. The restless, searching heart simply does not allow the eyes to close [אבן עזרא, מצודת דוד, תעלומות חכמה].

In contrast, other scholars understand this severe lack of sleep not as the result of deep philosophical seeking, but as a description of a wicked individual. Such a person is so consumed by an obsessive chase after wealth and the satisfaction of physical desires that his sleep constantly wanders, leaving him unable to rest [רש״י, צאינה וראינה].

A third, more spiritual perspective interprets this sleeplessness as a metaphor for ignoring human mortality. In this view, sleep represents death. The sleepless individual is one who intentionally avoids thinking about his final day. By refusing to reflect on his inevitable end, he actively prevents himself from repenting [תורה תמימה].