Sleep Fragmentation Does Not Explain Misperception of Latency or Total Sleep Time

Abstract

Study Objectives: Perception of sleep-wake times may differ from objective measures, although the mechanisms remain elusive. Quantifying the misperception phenotype involves two operational challenges: defining objective sleep latency and treating sleep latency and total sleep time as independent factors. We evaluated a novel approach to address these challenges and test the hypothesis that sleep fragmentation underlies misperception. Methods: We performed a retrospective analysis on patients with or without obstructive sleep apnea during overnight diagnostic polysomnography in our laboratory (n = 391; n = 252). We compared subjective and objective sleep-wake durations to characterize misperception. We introduce a new metric, sleep during subjective latency (SDSL), which captures latency misperception without defining objective sleep latency and allows correction for latency misperception when assessing total sleep time (TST) misperception. Results:The stage content of SDSL is related to latency misperception, but in the opposite manner as our hypothesis: those with > 20 minutes of SDSL had less N1%, more N3%, and lower transition frequency. After adjusting for misperceived sleep during subjective sleep latency, TST misperception was greater in those with longer bouts of REM and N2 stages (OSA patients) as well as N3 (non-OSA patients), which also did not support our hypothesis. Conclusions: Despite the advantages of SDSL as a phenotyping tool to overcome operational issues with quantifying misperception, our results argue against the hypothesis that light or fragmented sleep underlies misperception. Further investigation of sleep physiology utilizing alternative methods than that captured by conventional stages may yield additional mechanistic insights into misperception. I NTRO DUCTI O NAssessment of sleep often includes subjective reports of sleepwake durations, in clinical practice as well as epidemiological studies of sleep duration.1 However, when concurrent objective sleep measurements are available, it is not uncommon to observe that the subjective responses may differ. Underestimation of total sleep time has been previously observed in healthy adults under experimental circumstances, as well as insomnia patients during polysomnography (PSG).2-4 This phenomenon, sometimes termed misperception, may manifest as either overestimating sleep latency (SL) or underestimating total sleep time (TST), or both.4 Some patients with obstructive sleep apnea (OSA) may also exhibit misperception, though perhaps not to the same extent as those with insomnia symptoms. 5-7Several hypotheses have arisen regarding the basis for misperception, although a unified explanation remains elusive. For example, misperception has been linked with anxiety and mood, 3,8 personality traits, and sleep physiology measures such as electroencephalogram patterns of alpha-delta sleep or cyclic alternating pattern and high frequency electroencephalography (EEG) content. [9][10][11][12][13] In addition, we previously investigated possible relat...

Heart rate phenotypes and clinical correlates in a large cohort of adults without sleep apnea

“…Despite extensive work investigating the basis of misperception, the causes remain the subject of discussion. 36 , 39 , 63 We found that misperception of TST was associated with HR dipping, which runs counter to the prediction that dipping should reflect better sleep quality. TST misperception was only related to HRV frequency metrics derived from stage N1 and, in a manner that suggests more stable cardiac function, was related to greater misperception, which does not support the hypothesis that sympathetic tone contributes to the under-estimation of sleep.…”

“…However, we previously reported a similarly unexpected finding that misperception was associated with more stable sleep (fewer transitions) based on standard stage scoring. 39 …”

“…For measures of sleep perception, we used our recently described method of separating the latency and TST misperception. 39 In this way, misperception of TST is adjusted for sleep occurring during subjective SL to avoid double-counting among those with both onset and total sleep misperception.…”

Chronic Insomnia

“…Some degree of mismatch between the subjective experience and objective measurements of sleep is more common, 8 although the mechanisms remain uncertain. 18 In fact, selfreporting of sleep-wake times is influenced by many factors, including how the question is asked. 19 In a clinical field that is still defined entirely by the subjective experience, misperception among insomnia patients has until recently been considered little more than an academic curiosity.…”

Perceiving the Misperception

“…6 They performed a retrospective analysis on 643 patients who had PSG performed in their lab. The morning after their sleep study, all subjects were asked to estimate their total sleep time (TST).…”