Dement, W and Kleitman, N (1957), The relation of eye movements during sleep to dream activity: An objective method for the study of dreaming. Journal of Experimental Psychology, 53(5): 339–46

Summary

Researchers Dement and Kleitman looked at the relationship between rapid eye movements (REM) and dreams. A combination of EEGs, REM and non-REM sleep, experiments, correlations, and interviews were used in this study.

Psychology Being Investigated

In Dement and Kleitman’s study, the psychology being investigated encompasses several interrelated areas:

Sleep – The study delves into the complexities of sleep as a physiological and psychological state. It investigates the various stages of sleep, particularly focusing on the characteristics of these stages as they relate to dreaming. By examining the sleep cycle, the study contributes to understanding how different stages of sleep, especially the REM (Rapid Eye Movement) stage, are connected to the process of dreaming.

Dreaming – Central to the study is the exploration of dreaming – a complex cognitive and psychological process occurring predominantly during REM sleep. The study seeks to understand the nature of dreams, specifically how they can be physiologically indicated by rapid eye movements and whether these movements correlate with the dream’s content and duration. This aspect of the study is crucial for linking subjective dream experiences with objective physiological measures.

Ultradian Rhythms – Ultradian rhythms refer to biological cycles with a period shorter than 24 hours, often observed in the pattern of human sleep. Dement and Kleitman’s study contributes to the understanding of these rhythms, particularly focusing on the cyclical pattern of REM sleep that occurs multiple times during a typical night’s sleep. The investigation into ultradian rhythms in the context of sleep and dreaming sheds light on how these shorter biological cycles play a critical role in the structure and quality of sleep, as well as in the dreaming process.

Background to the Study

Observation of Rapid Eye Movements and Dream Recall – Aserinsky and Kleitman observed periods of rapid conjugate eye movements during sleep and found a high incidence of dream recall when subjects were awakened during these periods, and a low incidence when awakened at other times. They also confirmed the occurrence of these characteristic eye movements and their relation to dreaming in both normal subjects and schizophrenics. Additionally, they noted that these movements appeared at regular intervals in relation to cyclic changes in the depth of sleep during the night, as measured by the EEG​​.

Testing the Relation Between Eye Movements and Dream Content – Aserinsky and Kleitman also explored the relationship between eye movements and dream content to test whether they represented a specific expression of the visual experience of dreaming or were merely random motor discharges of a more active central nervous system​​.

Early Investigations on Dreaming and Brain Waves – Incidental observations were made on the occurrence of dreaming by investigators studying brain waves during sleep. These studies linked all stages of brain waves to dreaming but did not focus on whether actual dream content was recalled, and the number of reports by sleepers was generally very small. Other studies reviewed by Ramsey attempted to localize dream activity by awakening subjects at various times during the night, generally finding that dreams might be recalled at any time but were most frequently recalled in the later hours of sleep​​.

Aims

  1. Validation of REM as an Indicator of Dreaming – The study aimed to rigorously test whether rapid eye movements (REM) during sleep serve as a reliable physiological marker for dreaming.
  2. Correlation Between Dream Duration and REM – The study sought to examine whether the length of REM periods is associated with how long the dreams feel to the dreamer, effectively aiming to find a positive correlation between these two variables.
  3. Linking Eye Movements to Dream Content – The third aim was to ascertain whether the pattern of eye movements during REM sleep is related to the content of the dreams. This would help determine if eye movements are expressions of visual experiences within the dream, or merely random motor discharges.

Research Method

The study used a laboratory-based experimental method, focusing primarily on physiological measures such as brain waves and eye movements.

Sample Size and Demographics

The participants were nine adults, seven males and two females. The study focused intensively on five of these subjects, while the other four were used for validation purposes.

Experimental Design and Controls

Upon arrival at the lab, subjects were informed to abstain from alcohol or caffeine prior to the experiment. They were then equipped with electrodes near their eyes and on their scalp. These electrodes were designed to record eye movements and brain waves respectively, to understand sleep depth.

The subjects then went to sleep in a quiet, dark room. All electrode wires were carefully arranged to avoid tangling and to allow the subjects a comfortable range of movement during sleep.

Research Technique for Data Collection

Data collection was conducted using a Model III Grass Electroencephalograph located in an adjacent room. This machine recorded brain wave patterns and eye movements throughout the sleep period. The device operated at varying speeds to capture detailed and gross patterns of brain activity.

Measured and Manipulated Variables

  • Measured Variables: Depth of sleep (through brain waves), eye-movement potentials, and dream recall upon awakening.
  • Manipulated Variables: None explicitly stated, but one could argue that the act of waking up the subject to test dream recall could be considered a manipulated variable.

Additional Controls

The study made use of stringent controls to ensure accuracy. Subjects were required to abstain from substances that could affect sleep, and the sleep environment was carefully regulated to be quiet and dark. During the sleep period, the subjects were occasionally awakened to test their dream recall, but it’s noted that returning to sleep took less than 5 minutes.

Results

Validation of REM as an Indicator of Dreaming

Results showed that REM periods were consistently observed in all participants. The REM periods were characterized by a specific electroencephalogram (EEG) pattern distinct from deeper sleep stages. These findings lend support to the idea that REM serves as a physiological marker for dreaming.

Correlation Between Dream Duration and REM

The study found that participants were fairly accurate in estimating the length of their dreams based on REM duration, further strengthening the link between REM sleep and dreaming. This suggests a positive correlation between REM period lengths and perceived dream durations.

Linking Eye Movements to Dream Content

1. Vertical Movements: Rare but indicative of action in the vertical plane in the associated dreams. Examples of dreams included climbing ladders, watching climbers, and throwing basketballs.

2. Horizontal Movements: Also rare, observed once, linked to a dream where subjects were watching people throw tomatoes at each other.

3. Little or No Movement: This pattern was associated with dreams where subjects were watching something at a distance or staring at an object. For instance, driving a car and watching the road ahead.

4. Mixed Movements: These were the most common and were linked to dreams where subjects were looking at objects or people close to them.

5. Validation with Wakeful Subjects: Electrodes placed around the eyes during wakefulness demonstrated similar eye movement patterns to those in REM sleep, especially when subjects viewed close-up and distant activities.

Additional Observations

– REM periods occurred at fairly regular intervals throughout the night.

– A higher incidence of dream recall followed REM awakenings compared to non-REM awakenings.

– The ability to recall dreams did not significantly improve with practice.

Interpretation

The study provides strong evidence supporting REM as an indicator of dreaming. The correlation between REM duration and perceived dream length is also substantiated, albeit additional research could enrich these findings. The relationship between eye movements and dream content remains an area for further investigation.

Conclusion

Certainly. The study posits that Rapid Eye Movements (REMs) can serve as an objective indicator of dreaming. It notes that REMs happen in distinct episodes throughout a night’s sleep and are usually associated with dreaming, as validated by low-voltage EEG readings. Though it doesn’t rule out the possibility of dreaming during non-REM periods, the study suggests it’s less likely due to deeper brain wave activity at these times.

Moreover, the study contests the idea that dreams occur almost instantaneously. It found that the length of REM periods often matched the duration of dreams, suggesting that dreams unfold at a pace similar to real-life events.

The study’s impact lies in its ability to offer an objective measure for dream analysis. This is important as relying on self-reported dream recall can be subject to forgetfulness and subjective interpretation. This objective approach allows for the study of the impact of various external and internal factors on dreaming.

The findings are aligned with the well-established field of sleep research, although the precise mechanisms of dreaming and its relationship with physiological and psychological factors are still subjects of ongoing research.

Strengths 

  • Objective Measurements – One of the foremost strengths of Dement and Kleitman’s study is the use of objective physiological measures, such as Rapid Eye Movements (REMs) and low-voltage electroencephalograms (EEGs), to study dreaming. By observing REMs and EEGs, the researchers were able to provide empirical evidence for the correlation between these physiological processes and dreaming. This approach mitigates the limitations of subjective self-reports, which can be unreliable due to forgetfulness and subjective interpretation.
  • Internal Validity – The study’s design minimised confounding variables by maintaining controlled conditions, such as the sleep environment and timing of awakenings. By doing so, the researchers could be more confident that the relationship observed between REM and dreaming was not influenced by external factors, thereby enhancing the internal validity of the study.
  • Consistency in Observing Rapid Eye Movements in All Subjects – The study observed discrete periods of rapid eye movements in all nine subjects every night they slept. This consistency across subjects and over multiple nights added credibility to the findings and supported the hypothesis that REM periods are a regular and intrinsic part of normal sleep. This consistency was crucial for establishing the generalizability of the study’s findings regarding the relationship between REM sleep and dreaming​

Weaknesses

  • Small Sample Size – may not be representative due to its limited demographic diversity and small size. Predominantly consisting of adult male university students, the sample lacked variation in age, gender, and cultural background, which could affect sleep patterns and dream experiences. This homogeneity limits the generalizability of the findings to the wider population. Additionally, a small sample size reduces the likelihood of capturing the full spectrum of variability in sleep and dreaming behaviours present in the general population. Such limitations in sample representativeness can challenge the external validity of the study’s conclusions.
  • Subjective Nature of Dream Recall – While the study attempts to correlate REM sleep with dreaming, the evidence relies partly on participants’ self-reported experiences of dreaming, which can be prone to recall bias or inaccuracies, affecting the study’s internal validity.
  • Ethical Concerns – The ethical concerns in Dement and Kleitman’s 1957 study, which involved waking participants during their sleep to inquire about dream experiences, are significant both ethically and methodologically. Ethically, the disruption of natural sleep patterns raises concerns about the well-being and informed consent of the participants, as sleep is vital for health and cognitive function, and participants might not have been fully aware of the potential consequences of sleep interruption. Methodologically, this approach introduces an extraneous variable, as the act of being awakened can influence dream recall and potentially alter the nature of dream content, thereby affecting the study’s outcomes.

Questions

1. What are the potential limitations of using self-reported dream recall in studying dreams?
2. Why is it important to take an objective approach when studying dreams?
3. What factors did the study control to ensure internal validity?
4. What are the potential benefits of using an experimental approach in studying dreams?
5. How can the study’s findings contribute to the development of interventions for sleep-related issues?
6. Discuss the potential benefits and drawbacks of using objective measurements, such as REMs and electroencephalograms (EEGs), in studying dreaming. How do these objective measurements enhance or limit our understanding of the dream experience?