Deep Sleep Evolved with Descent from Trees,researchers Find
BARCELONA,SPAIN – A growing body of research suggests a pivotal link between humanity’s evolutionary descent from arboreal life and the development of deep,restorative sleep. While the biological mechanisms of sleep – involving melatonin,glucose,cortisol,and brainwave phases – have long been understood,the why of consolidated,nightly sleep remains a subject of intense study. New findings indicate that shifting from sleeping in trees to sleeping on the ground necessitated a more profound and protective sleep state.
For our primate ancestors, life in the trees offered inherent security. Sleeping aloft meant relative safety from predators, reducing the need for extended periods of deep sleep. Though, coming down from the trees exposed early humans to increased vulnerability. This environmental shift, researchers believe, drove the evolution of deeper sleep phases - particularly slow-wave sleep – as a survival mechanism.
“Our bodies are genetically programmed to make changes throughout our development,and sleep is no exception,” explains sleep expert Madrid,whose work highlights the varying sleep patterns across the human lifespan. The deepest and most restorative phase of sleep, crucial for physical recovery, became increasingly importent as humans adapted to terrestrial life.
This evolutionary pressure coincides with a important historical turning point: the Industrial Revolution and the advent of artificial light. Prior to these developments, human sleep patterns were intrinsically linked to natural daylight cycles. The shift to schedules dictated by artificial illumination has contributed to a rise in sleep disorders – now numbering over eighty – disrupting the natural rhythms honed over millennia.
Experts now recommend prioritizing exposure to natural daylight upon waking and minimizing exposure to blue light from screens in the hours leading up to bedtime. “ideally, as soon as we get out of bed, we should be exposed to natural daylight; and three hours before going to sleep, we should be in a warm light environment, not the white or blue light of screens,” Madrid advises. This return to aligning with natural light cycles may help restore the deep, restorative sleep that evolved alongside our ancestors’ journey down from the trees.
