Is static in the bed sheets dangerous?

No, this type of static electricity (which can build up around the house, on carpeting, blankets, clothes, or while brushing hair) is not harmful to the body except for a momentary shock.

Face

A person grows .3 inches while sleeping. 

However, they will shrink down to normal once gravity pushes against their bones when they wake.

Myth

The moon’s gravity pulling on water causes the tides.

This is only partly true.

The moon does pull on ocean water, but that tug at any one point is about 10 million times weaker than Earth’s gravity. It’s really the interplay of gravity between the moon, Earth, and sun that creates a tidal force, and it’s more of a “push” than a “pull.”

Each molecule of water is pulled by the moon’s gravity, but alone that acceleration is so weak it isn’t noticeable. Because ocean water covers about 71% of Earth’s surface and is connected as one liquid body, however, all of those tiny tugs add up to form a significant pressure — the tidal force.

Molecules of water near the poles are pulled mostly straight down, those on the face of Earth closest to the moon experience the strongest pull toward the moon, and those on the opposite side of Earth feel the weakest acceleration.

Together, these interactions form a pressure on seawater that generally directs it away from the poles and toward the equator, where it’s strong enough to fight gravity to form two bulges: the high tides.