I have a somewhat general question regarding the wakefulness stage during sleep. I'm currently looking at the hypnogram data in the XML files from both the nsrr and profusion annotations. It looks one can have many episodes of wakefulness during sleep (figure below shows about 25 episodes and many subjects have hypnograms like this). Since wakefulness is a conscious state (i.e. one knows that he's awake and can perceive the environment), I wonder if one can have that many brief episodes of wakefulness at night even considering the aging population from the MESA study. Are there any artifacts in the hypnogram data? Does any filter need to be applied? I'm asking as a non-expert in sleep analysis.
Thanks for checking out the resource. I emailed another NSRR team member to get her feedback. My inkling is that this sort of pattern is within the normal range. I believe people can have many short awakenings over the course of a night and not "remember being awake", so to speak, in the morning.
I doubled checked the data shown in the hypnogram to the previously scored study just to make sure that it is correct, and the hypnograms match. Multiple awakenings are often observed throughout the sleep period. Often people are not aware of these awakenings. You can view the following resource on sleep cycles: https://sleepdisorders.sleepfoundation.org/chapter-1-normal-sleep/sleep-regulation/. Artifacts are taken into consideration when deriving sleep stages and filtering is generally applied before the hypnogram is derived.
Hi Mike and Stephanie,
Thank you very much for double-checking and a great resource. That helps a lot!