How many hours do you sleep? A comparison of subjective and objective sleep duration measures in a sample of insomnia patients and good sleepers

Abstract

Our objective was to assess the agreement and linear relationships amongst multiple measures of sleep duration in a sample of patients with insomnia disorder and good sleeper controls. We retrospectively analysed data from 123 patients with insomnia disorder and 123 age-and gender-matched good sleeper controls who completed a simple subjective habitual sleep duration question (Pittsburgh Sleep Quality Index), a sleep diary (5-14 days), 2 nights of polysomnography, and two corresponding morning subjective estimates of sleep duration. Descriptive statistics, linear regression analyses and Bland-Altman plots were used to describe the relationship and (dis)agreement between sleep duration measures. Relationships between polysomnography and the simple question as well as between polysomnography and sleep diary were weak to non-existent. Subjective measures and polysomnography did not agree. Sleep duration measured with the Pittsburgh Sleep Quality Index or sleep diary was about 2 hr above or up to 4 hr below polysomnography-measured sleep duration. Patients with insomnia disorder, on average, reported shorter sleep duration compared with polysomnography, while good sleeper controls, on average, reported longer sleep duration compared with polysomnography.The results suggest that subjective and objective measures apparently capture different aspects of sleep, even when nominally addressing the same value (sleep duration). They disagree in both patients with insomnia disorder and good sleeper controls, but in different directions. Studies assessing sleep duration should take into account both the investigated population and the assessment method when interpreting results. Future studies should continue to investigate possible psychological and physiological correlates of sleep (mis)perception.

The relationship between mental health, sleep quality, and the immunogenicity of COVID-19 vaccinations

“…Our null finding on the relationship between sleep quality and vaccine immunogenicity is in line with previous work that found an impact of sleep duration, but not of sleep quality or sleep efficiency on the post-vaccination humoral immune response for hepatitis B and influenza vaccinations (Prather et al, 2012; Prather et al, 2021) as well as with the finding that sleep disruptions resulting from sleep apnoea do not affect antibody titres following an influenza vaccination (Dopp et al, 2007). The difference between the clear effect of sleep restriction and sleep deprivation on vaccine immunogenicity (Dopp et al, 2007), at least in the short term (Benedict et al, 2012; Spiegel et al, 2002) and the absence of an impact of sleep quality or sleep efficacy might be explained by the large discrepancy between subjective and objective sleep variables, even in good sleepers (Benz et al, 2022).…”

“…However, our results suggest that low sleep quality or mental health conditions in general have no relevant impact on antibody titres following COVID-19 booster vaccinations, especially compared to established mediators of COVID-19 vaccine immunogenicity, specifically age, smoking, and interval to the last immunising event (Reusch et al, 2022). While insomnia patients generally underestimate their sleep (Benz et al, 2022), polysomnographic measurements provide evidence for an objective reduction of sleep time in insomnia cohorts (Baglioni et al, 2014). Only studies including objective and subjective sleep measurements that are currently under way will be able to disentangle the impact of sleep quality and sleep duration on COVID-19 vaccinations (Lammers-van der Holst et al, 2022).…”

The importance and limitations of polysomnography in insomnia disorder—a critical appraisal

“…Patients with ID typically display a pronounced discrepancy between objective, PSG-derived sleep parameters and the respective subjective reports (Benz et al, 2023). It has been proposed that the value of this discrepancy can be used to identify another specific 'sleep misperception' ID subtype (Edinger & Krystal, 2003).…”

Insomnia and REM sleep instability

“…To pinpoint the possible physiological mechanism in insomnia, the approach presented above was mainly driven by the comparison between subjective and PSG sleep parameters for specific nights, and partially even within specific sleep stages, taking the unsatisfying quality of sleep in insomnia itself as an indicator of modified sleep. One problem with this idea is the discrepancy between different subjective accounts (Benz et al, 2023): in insomnia, longer retrospective accounts such as by the Pittsburgh Sleep Quality Index (Buysse et al, 1989) are typically much more negative than accounts relating to the night that just passed. Tang et al (2023) recently showed that the judgement about sleep quality already changes over the course of the following day.…”

“…It is an ongoing question what determines the subjective sleep or wake times individuals indicate in questionnaires. Experimentally, the answer depends on whether the last night or typical sleep in the recent past is assessed, whether sleep or wake times have to be reported (Benz et al, 2023) – even though they can be computed from one another—and on the time of assessment on the following day (Tang et al, 2023). It is maybe too obvious to be stated that humans have no explicit concept of different sleep stages – not even the qualitatively so different NREM and REM divisions – and therefore cannot remember and report them.…”