Gravity is a natural phenomenon that affects all things particularly all living creatures from cell to human being. It has an infinite range, although its effects become weaker on farther objects. This article is not based on observation on either human or animal. But it is based on extensive and attentive results of scientific studies on sleep performed in ground, water and space. Since the effect of gravity on sleep has been rarely studied and medical aspects give much of attention. Man live in the presence of gravity for million years but with the advent of space flight. Man can able to live in the absence of gravity.
Why do we sleep?
The hypothesis presented here is that sleep is partly due to gravity. It try to explained several theories why sleep is a part of life in which it is one parameter. That all creatures on Earth undergo an alternative wake and sleep periods. Like in water, species modes of sleep are different from those of mammals. In which the rapid eye movement phase of sleep is not apparent, like in fishes. For insect, it is believed that there are alternating active and passive periods. Even planktons and unicellular organisms correspond to the necessity of using energy. In which it tends to move lower at night and goes up to the surface during daytime.
On the ground, gravity influence REM (Rapid Eye Movement) sleep wherein muscle tone helps maintain posture. When asleep the brain decreases its sensitivity to the external stimulus like sound, light, contact and weight. Like for example, horses can sleep while standing locking their knees to stay upright. But they cannot achieve REM sleep if they will not lay on the ground, the same also in the elephants. Indeed, gravity is forgotten by the brain during REM sleep.
In space, many studies explained that sleep differs minimally from Earth in which sleep duration in space is shorter. Sleep is one concern in space but the absence of gravity affects muscles and bones. Absence of it produces atrophy of muscles and loss of strength in bones in which these two are important in sleep. In water also demonstrate that biological sleep is dependent on gravity because without it sleep is reduced.
Therefore, evidences shows that sleep depends on the gravity that acts on the body either in water, space and ground. When gravity is compensated, sleep is affected. Because there is no tool to suppress gravity, it is hard to ascertain a long term experiment over generations to confirm that sleep is due to gravity.
Source: Prepared by Joan Tura from Medical Hypotheses
Volume 113, April 2018, Pages 81–84