Dement & Kleitman’s (1957) sleep study concluded that REM sleep was linked with dreams. Participants, when woken up shortly after REM sleep, were more likely to remember their dreams than those who were woken up long after REM sleep. Additionally the researchers concluded that direction of the eye movement also correlated with dreams, for example when dreaming of watching someone climbing a ladder, one participant’s REM pattern was mainly vertical.
There is no denying that this was at the time ground breaking research, using EEG machines (at the time a new technology). However was the sleep from participants really natural? There have been arguments against how natural the sleep from participants was. Firstly participants were in a laboratory which they had never visited before, therefore it was an unusual location for them to sleep, which could have affected their natural sleep. Secondly participants had to sleep with an EEG machine electrodes attached to their heads. Im not sure about you, but this would definitely affect my sleep.
My point is that if participants sleep was unnatural then the whole results from this experiment could be invalid. If the participants were sleeping outside their natural habitat, how can researchers be sure that their sleep was the same as their sleep at home, and that they had similar dreaming patterns, etc. meaning the study had a low ecological validity.
Dement and Kleitman used controls which they claimed would help cause natural sleep, such as not consuming caffeine or alcohol 48 hours prior to the experiment, however they didn’t take into account that the environment the participant had to sleep in.
In conclusion, the method used in Dement and Kleitman’s study lacked validity, however it could be put down too technology of the time, as an EEG machine may have had to be used in a lab setting. Bar the obvious methodological faults in the study, Dement and Kleitman’s research is still widely accepted today in psychology and results have yet to be refuted, meaning currently their results are still valid.
psueef 
Really interesting blog, and i agree with you that the study may have been in a lab setting because of the use of an EEG machine, which would then affect the nature of the sleep a participant would have. Another element could be infact the anticipation of being recorded and looked at while asleep, could infact effect the results? If i was in position where i was aware i was being looked at, i would not be able to relax and be in my natural state. However i feel that their results are infact still valid as such a thing as sleep, it is very hard to measure in a natural setting.
I find the study by Dement and Kleitman (1957) quite interesting, but I agree that there are many issues with the research. The sample used in the study consisted of only nine participants, of which only five were studied in depth. In addition to this, only two of these participants were female. This means that the results cannot be reliably generalised to the entire population as the sample may not be representative of all people, particularly females.
I agree that perhaps the environment that the participants slept in may have affected the sleep that was gained, but with many controls in place, the results seem quite reliable. People sleep in different places quite a lot of the time that may not be similar to their normal environment. For example, people camp in fields and are able to sleep, and this is not similar to their normal sleeping environment, or at least for the majority of campers. Although you state that comfort may have been an issue because of the electrodes being attached to the heads of the participants, a control was put in place to ensure that comfort was not greatly affected.
The use of EEG allowed for objective results to be collected, although subjective qualitative data was collected from participants when they were asked to describe their dreams. Overall though, I think that the study could still be classed as being both reliable and valid, although there is a lack of generalisability.
Reference:
Dement, W., & 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), 339-346. doi: 10.1037/h0048189
Although the participants may have been uncomfortable while they slept due to the unnatural environment that they slept in, there was no other way that it was possible to do this study in an environment that the participants felt that they were at home. The main problem with sleeping somewhere unfamiliar or uncomfortable would be trying to get to sleep, and the fact they slept soundly enough to get to REM sleep and deep sleep suggests that the unfamiliar environment was not an issue. When people are asleep they are unconscious and unaware of their surroundings, so being in a lab would not affect their eye movements during REM sleep. Although this study might have been generalised to the population better if the sample size was bigger.
Could someone please tell me if this study is reliable and valid, please explain why.
I personally believe this study to an extent. The lower our body temperature drops is the deeper we get into our sleep, at our lowest body temperature we usually are in a state of dreaming. However this study as you said was also done in an unnatural environment with unnatural objects being placed on the participants. It would be interesting for someone to replicate this study with people being able to do their usual routine and being studied in a different way. When people are in their own home in their own bed the results I believe could differ a large amount. This study is still extremely interesting and is good to reflect on.