Bed coverings were historically luxury items unaffordable for most people. From Egyptian linen to Roman wool, bedding marked wealth status. By the Early Modern period, beds became the most expensive household item, representing about one-third of total possessions. Today, anthropological research shows even tropical cultures use some covering, with only nomadic foragers regularly sleeping without protection against nighttime temperature drops.

The human body naturally cools before sleep, triggering melatonin release. During REM sleep, thermoregulation fails, resembling "reptilian" temperature control. This coincides with the coldest part of night, creating a physiological need for external warmth. Studies show weighted blankets can increase serotonin production, addressing the neurotransmitter drop during REM sleep and explaining why coverings provide comfort beyond mere temperature regulation.

Behavioral conditioning plays a significant role in our blanket preference. Children learn to associate being covered with sleep, creating a Pavlovian response. While womb security theories exist, experts find them unlikely. The blanket serves practical, physiological needs while providing psychological comfort, explaining why even in hot climates, humans rarely sleep completely uncovered despite temperature discomfort.