I have a few questions regarding SHHS1 data:
Is there a good way to get subjective sleep efficiency (SE)? From the morning survey, I was thinking of using hwlghr10 & hwlgmn10 (how long slept in hrs/minutes) as total subjective sleep time, then adding minfa10 (minutes to fall asleep) to get the subjective time in bed, but I don't know how to get subjective time awake during the night. Thoughts?
There is data available for objective SE calculated from PSG: https://sleepdata.org/datasets/shhs/variables/slp_eff, but there were many missing values in the actual dataset for this variable. I noticed there's also a measure explicitly marked "PSG Report (SHHS2): Sleep Efficiency:" https://sleepdata.org/datasets/shhs/variables/slpeffp, but this is also in the SHHS1 dataset. The slpeffp values match existing slp_eff values as well as the missing values of slp_eff (100*SlpPrdP/TimeBedP, when slp_eff is blank for some reason). So, what's the difference between slp_eff and slpeffp, and is it all right to use the latter for SHHS1?
Any answers or guidance would be appreciated! Thanks,
Thanks for inquiring and checking out the SHHS data. Good questions!
My initial thought is that subjective sleep efficiency would be difficult to assess in SHHS. On other sleep diaries we often have questions about awakenings during the night, yet the "Morning Survey" you cited is limited in that it doesn't really ask any questions about the time between going to sleep and waking up (besides Q4 for a subjective quality rating).
An accurate sleep efficiency measurement in SHHS1 was difficult to ascertain due to some of the limitations of the home sleep testing devices. As such, the slp_eff variable filters out many cases where it was noted during scoring that the entire in bed period may not have been captured on the recording. Some of the Signal Quality variables were used to censor values from slp_eff. Variables like latreliable, restan2, and restan3 were probably used. I think the exact filtering code may have been lost over time, though it has been on my back-back-burner to try and reverse engineer the filters that were used and make these more apparent in the variable metadata.
To the question about if it's "all right" to use slpeffp in SHHS1, it's a decision that each researcher can make to filter on certain criteria or not. Some of the efficiency values are probably not all that reliable. Unfortunately, this is one of the prevailing problems in analyzing SHHS1 data and the issue comes up fairly often. Thankfully most of the other studies do not share these sleep latency/efficiency challenges!
Thank you for the swift and informative reply! The missing values in slp_eff make more sense now, and my team will end up using this variable. We just came up with some questions that aren't relevant to sleep efficiency, but since I'm already here...
Is there any information about retirement/career status? I was unable to find it in the dictionary.
We're also interested in grouping by date, if possible. The variable representing the "date questionnaire was completed (days from index date)" (https://sleepdata.org/datasets/shhs/variables/date10) seems like a good starting point, but what does "index date" mean and where can it be found?
I don't see anything about retirement/career status in our SHHS datasets. I suspect this is known within the parent cohorts (e.g. Framingham, ARIC, CHS), yet wasn't pulled over by the dataset owners into the official SHHS datasets. To get at this information you would probably have to access the parent cohort datasets and SHHS dataset on BioLINCC, which has its own set of access rules.
As for dates, these were purposefully removed upon posting to BioLINCC (which we use as the source for NSRR) for de-identification purposes. The "index date" referenced throughout indicates the "date of the baseline polysomnogram", which essentially represents "date of the SHHS1 visit". I think we have sent other users the "year of index date" (e.g. 1995 or 1996 in most cases for SHHS1) in a secondary dataset before, so I could get that for you if it would be of any help. Unfortunately we aren't permitted to share anything more specific.