Monkeys sleep in trees, often taking their time to select the best tree to sleep in overnight. Researchers have found that the tree selection depends on the monkey species, with different species preferring to sleep in different kinds of trees.
The monkey will select a tree based on the location of predators and the distance to food sources. They will also look to see where other monkeys are choosing to sleep in relation to their spot so that they choose an area with less competition for food. Most monkeys spend at least 12 hours of their day either sleeping or nesting in their sleeping trees. The owl monkey sleeps for 17 hours per day, the rhesus monkey sleeps for 11.8 hours per day and the squirrel monkey sleeps for approximately 9.9 hours each day.
One problem that faces monkeys in their sleep quest is human destruction of habitat. Humans have been destroying the forest and jungle areas where the monkey species live, including destroying the trees. This creates problems for the monkeys who are sometimes unable to find suitable places to sleep. It also means that monkeys are forced to sleep closer and closer to an encroaching human population. This leaves the monkeys vulnerable to human interaction as well as prone to eating human food that leaves them obese and unhealthy.