Biological approach: Dement and Kleitman (sleep and dreams)

Psychology AS · The core studies. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.

Test this topic free All Psychology AS topics

The idea

Dement and Kleitman (1957) wanted an objective way to study dreaming. Sleep follows an ultradian rhythm: a cycle of REM (rapid eye movement) and non-REM sleep that repeats several times in one night. They asked whether REM sleep is the time when we dream.

Nine adults slept in a laboratory with electrodes near the eyes and on the scalp. The EEG showed REM as fast, low-voltage brain waves with bursts of eye movement. Sleepers were woken by a bell, in REM or in non-REM sleep, and said at once whether they had been dreaming and what about.

Dreams were recalled after most REM awakenings and after very few non-REM ones. REM sleep can therefore be used as a physical sign of dreaming.

Rules to remember

Sample: 9 adults (7 men, 2 women), 5 studied in detail. They avoided alcohol and caffeine on the day of testing.
Method: laboratory experiment with repeated measures (each sleeper woken in REM and in non-REM), plus a correlation and a short interview after each waking.
Recall: dreams reported after about 80% of REM awakenings (152 of 191) but only about 7% of non-REM awakenings (11 of 160).
Length: woken after 5 or 15 minutes of REM, sleepers usually chose the right length (45 of 51 correct for 5 minutes, 47 of 60 for 15 minutes).
Direction: eye movements fitted the dream, e.g. up and down movements when the dreamer was climbing ladders.
Strengths: the EEG is objective and the controls were good. Weaknesses: small sample, an unnatural place to sleep, and dream reports that cannot be checked.

Common mistake

Students mix up ultradian and circadian rhythms. Ultradian means the cycle repeats more than once in 24 hours (the REM and non-REM cycle); circadian means once every 24 hours (the sleep-wake cycle).

Worked example

A student writes: "Dement and Kleitman proved that dreaming happens only in REM sleep." Is this statement correct?

Dreams were reported after 152 of 191 REM awakenings, so REM and dreaming are strongly linked.
But 11 of 160 non-REM awakenings also gave a dream report, so dreams were not limited to REM.
The study found an association. It did not show that REM causes dreams or that non-REM sleep has no dreams.

Answer: No. The correct conclusion is that dreaming is closely associated with REM sleep, not that it happens only in REM.

Ask about this

Type what you are stuck on. The helper finds the explanation, worked examples and the notes to read, free and instant.

Keep going

Biological approach: Hassett et al. (monkey toy preferences) →Take a Psychology AS test