Stressed-out students at an increasing number of universities can forget about catching winks in a hammock, because school officials are more worried about the stress the sling-style bedding puts on trees.

Michigan State University is one of the latest schools to ban hammocking, after determining the rope-and-canvas island staples put too much pressure on trees. 

“We’re not anti-hammock," Frank Telewski, a Michigan State plant biology professor and curator of the campus arboretum, told The Wall Street Journal. "We’re anti-tree damage.”

No attachments can be made to trees on the Spartan campus, according to Telewski, who said in an official statement the only exception is for the Red Ribbon Project for World AIDS Awareness Day, when the organizing group puts ribbons on trees and then removes them 24 hours later.

"This includes not locking bicycles or any other portable devices to trees; not tying posters, flags, kites, banners, tents or tarps to trees; not affixing via string, rope, twine, cordage, wire, staples, cable ties, tape, nails, screws or any other type of fastener any sort of signs, posters, bulletins or any other type of flier to trees," reads part of the statement.

Last spring, the school posted “No hammocking, please” signs along the Red Cedar River, which winds through the East Lansing campus and past a grove of century-old pines near the hockey arena. The penalties could range up to $100 fines and even jail time, although no one has been punished yet. A similar ban has been put into place at Auburn University, andofficials at other schools have urged students to stretch their hammocks between freestanding poles, not trees.

Despite the ban, hammocks are more popular than ever, according to the Journal, with sales having doubled over the past two years.

Several schools have already banned "slacklining," in which webbing with a crank system is attached between two trees and tightened so enthusiasts can practice tight-rope walking.

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