Ch. 8.3. Why Sleep? Why REM? Why Dreams?

Question 1

What might one predict about the sleep of fish that live deep in the ocean?

Answer 1

The deep ocean, like a cave, has no light and no difference between day and night. These fish might not need to sleep because they are equally efficient at all times of day and have no reason to conserve energy at one time more than another.

Question 2

What kind of animal tends to get more than the average amount of sleep?

Answer 2

Predators get much sleep, and so do species that are unlikely to be attacked during their sleep (such as armadillos).

Question 3

How does weakening synapses during sleep improve
memory?

Answer 3

Weakening the less active synapses enables the strengthened ones to stand out by contrast.

Question 4

What kinds of individuals get more REM sleep than others?
(Think in terms of age, species, and long versus short sleepers.)

Answer 4

Much REM sleep is more typical of the young than the old, and of those who get much sleep than those who get little

Question 5

According to the neurocognitive hypothesis, why do we have visual imagery during dreams? Why do dreams sometimes make an incoherent or illogical story?

Answer 5

We have visual imagery because areas of the visual cortex other than the primary visual cortex become active, without any input from the eyes.

Dreams are sometimes incoherent or illogical because low activity in the prefrontal cortex means poor memory for what has just happened.