dement and kleitman’s (1957) study of REM sleep and dreaming

Question 1

What were the researchers three main aims

Answer 1

-To investigate the relationship between dreaming and sleep stages.

-To investigate whether eye movements during REM were connected to dream content.

-To investigate whether there is an objective way to measure dreaming.

Question 2

Method/Procedure

Answer 2

Dement and Kleitman used nine participants: seven male and two female. This was a laboratory experiment during which participants slept whilst attached to a polysomnography (PSG). A PSG is a measure of sleep during which various electrodes are attached to the body in order to record biophysical changes. PSGs monitor various bodily functions such as brain activity using an EEG and eye movement using an EOG.

The participants had been told to avoid alcohol and caffeine that day. During their sleep, they were woken several times during the night by researchers and asked if they had been dreaming and if so, what their dream was about and how long it had lasted.

Question 3

Results

Answer 3

The researchers found that participants reported they had been dreaming if they were woken during REM sleep 80% of the time compared to during non-REM sleep (9% of the time).

They also said that their dream was shorter if they had been woken 5 minutes into REM, whereas if they were woken up 15 minutes in they said it was longer.

Finally, they found there was a connection between eye movements and content of the dream. For example, one participant reported a dream about tomatoes being thrown whilst having horizontal eye movements. Another had vertical eye movements whilst reporting dreaming about going up a ladder.

Question 4

Conclusion

Answer 4

Dement and Kleitman concluded that:

Dreaming occurs most often during REM sleep
Eye movement is connected to the content of our dreams
The length of dreams can be accurately judged by the dreamer

Question 5

Evaluation Strengths

Answer 5

This was a laboratory experiment using an objective measure of sleep. This is a strength because extraneous variables could be highly controlled and the use of a PSG means accurate measurements of eye movement and brainwaves could be reported.

This study removed demand characteristics by using a ‘single-blind’ design – this means that when participants were awakened they did not know and were not told whether they had been woken during REM or non-REM sleep before recording their dream.

Participants were asked to avoid alcohol and caffeine before the study. This is a strength because it means that external factors that may have impacted results were controlled and removed, making data more reliable.

Question 6

Evaluation Weaknesses

Answer 6

This study used a very low sample of nine adults and there was also a gender imbalance. These results cannot be generalised to a wider population.

This was an extremely artificial setting during which participants were attached to wires and woken up throughout the night. Therefore, it doesn’t reflect a ‘real’ night’s sleep and therefore lacks ecological validity. Furthermore, this may have affected the quality of sleep participants experienced which reduces validity of the results.

It cannot be concluded that dreams only occur during REM sleep from this study. Rather, that the recall of dreams is stronger in REM sleep than non-REM.