Combining Wake-Up-Back-to-Bed with Cognitive Induction Techniques: Does Earlier Sleep Interruption Reduce Lucid Dream Induction Rate?
Round 1
Reviewer 1 Report
A paper helps to understand how different sleep duration and interruption study designs may affect lucid dream induction rate. The following questions are intended to clarify several issues that can be of interest to the wider auditory of readers.
1. Since it is known that ultradian rhythms of NREM-REM sleep exists, I wonder, how the authors comment possibility that earlier sleep interruption / shortening sleep duration in the reported protocol to 4.5 hours instead of previously used 6-hours-of-sleep-protocol could impact probability REM sleep occurrence due to falling out-of-ultradian-phase?
2. I wonder, what is the authors’ opinion regarding the possibility that lucid dreams induction, assessed on a particular day of the week, may depend on personal sleep phase, chronotype (morningness-eveningness preference), or influenced by social jet-lag score?
3. Is there any scientific evidence regarding the relationship between dream recall and the endogenous circadian period and its precision?
4. It was shown that dream recall can be associated with individual melatonin production. Could it be that obtained results may be linked with different circadian phases and melatonin phases depending on the circadian timing of sleep interruption?
5. Table 1: what statistical method was applied to obtain F and p-values. There are 3 groups and asterisks are not explained to specify between what groups there are significant differences.
6. Are there significant sex-related differences in the main outcomes of the study?
7. What is the known impact of the phase of the menstrual cycle in women on the lucid dream induction rate?
Author Response
Review #1
A paper helps to understand how different sleep duration and interruption study designs may affect lucid dream induction rate. The following questions are intended to clarify several issues that can be of interest to the wider auditory of readers.
Dear Reviewer
Thank you for your effort and the positive feedback. We appreciate the constructive suggestions and questions, and try to comment on all points, as seen by the point-by-point responses.
Comment #1
- Since it is known that ultradian rhythms of NREM-REM sleep exists, I wonder, how the authors comment possibility that earlier sleep interruption / shortening sleep duration in the reported protocol to 4.5 hours instead of previously used 6-hours-of-sleep-protocol could impact probability REM sleep occurrence due to falling out-of-ultradian-phase?
Indeed, this is very good question. The reason to shorten the original protocol was to shorten the total duration of the night recordings that the recordings lasted sometimes until 10 in the morning. While shortening the first part of the night we tried to keep up the 90-minute NREM-REM cycles (1.5-3.0-4.5-6.0) furthermore the 4.5 was an approximation because we still waited for the following REM period to do the awakening, however, we did not control for possible interfering and underlying circadian processes.
We added this point to the discussion
Comment #2
- I wonder, what is the authors’ opinion regarding the possibility that lucid dreams induction, assessed on a particular day of the week, may depend on personal sleep phase, chronotype (morningness-eveningness preference), or influenced by social jet-lag score?
This is a good question and we would have loved to have the financial resources at that time to control for such effects, however, without financial support every additional factor to control for is another set of 10-20 recording nights that we could not afford at that time.
Comment #3
- Is there any scientific evidence regarding the relationship between dream recall and the endogenous circadian period and its precision?
Sorry, we are not aware of such an effect. Usually, neural correlates are discussed with dream recall rate (e.g. Siclari, F., Baird, B., Perogamvros, L., Bernardi, G., LaRocque, J. J., Riedner, B., . . . Tononi, G. (2017). The neural correlates of dreaming. Nature Neuroscience, 20, 872. doi:10.1038/nn.4545). However, we added the point that circadian processes might have an effect.
Comment #4
- It was shown that dream recall can be associated with individual melatonin production. Could it be that obtained results may be linked with different circadian phases and melatonin phases depending on the circadian timing of sleep interruption?
See above.
Comment #5
- Table 1: what statistical method was applied to obtain F and p-values. There are 3 groups and asterisks are not explained to specify between what groups there are significant differences.
We added the information of the statistical method (ANOVA). Furthermore, we added the asterisks for the post-hoc analysis.
Comment #6
- Are there significant sex-related differences in the main outcomes of the study?
No statistically significant sex differences, however, for this analysis the test was under powered.
Comment #7
- What is the known impact of the phase of the menstrual cycle in women on the lucid dream induction rate?
We are not aware of any studies on LD induction and menstrual cycle in women. We added a note in the discussion
Reviewer 2 Report
Authors presented the paper entitled Combining wake-up-back-to-bed with cognitive induction techniques: Does earlier sleep interruption reduce lucid dream induction rate? for the peer review. This topic is of great interest to the somnologists.
Some issues should be resolved. First, Ethics committee protocol is missing.
Second, have you controlled the light intensity during the experiments?
Third, have you checked the effect of menstrual cycle in women on lucid dreaming?
Author Response
Authors presented the paper entitled Combining wake-up-back-to-bed with cognitive induction techniques: Does earlier sleep interruption reduce lucid dream induction rate? for the peer review. This topic is of great interest to the somnologists.
We appreciate the comments and suggestions provided.
Some issues should be resolved. First, Ethics committee protocol is missing.
We added the information on ethics.
Second, have you controlled the light intensity during the experiments?
No, we did not control for light intensity. However, the light was not varied during the recording nights – at least within the experiments. We added a note in the methods.
Third, have you checked the effect of menstrual cycle in women on lucid dreaming?
No, we did not check for menstrual cycle in women. However, we are not aware of any studies on LD induction and menstrual cycle in women. We added a note in the methods and discussed this issue briefly.
Round 2
Reviewer 2 Report
You have addressed all my iisues. Thank you.
