The DBST index - Discrepancy between desired time in bed and desired total sleep time: A pilot study for the possible new sleep index predicting severity of insomnia

Abstract

ObjectivesWe considered the concept of the discrepancy between a patient's desired time in bed (TIB) and total sleep time (TST), which we termed the DBST. DBST can be used to easily assess a patient’s thoughts on their desired TST and dysfunctionally long TIB. This study aimed to explore whether the DBST can predict the severity of insomnia or dysfunctional beliefs regarding sleep among the general population.MethodsA total of 374 members of the general population participated in this e-survey study. The participants answered questions regarding their bedtime, sleep onset time, wake-up time, desired TST, and desired TIB, and psychological symptoms were assessed using the Insomnia Severity Index (ISI), Patients Health Questionnaire-9 items (PHQ-9), Dysfunctional Beliefs and Attitudes about Sleep-16 items (DBAS-16), and Glasgow Sleep Effort Scale (GSES).ResultsThe DBST was significantly correlated with the ISI (r = 0.19, p < 0.01), PHQ-9 (r = 0.13, p < 0.05), GSES (r = 0.13, p < 0.05), DBAS-16 (r = 0.18, p < 0.01), wake-up time (r = -0.11, p < 0.05), desired TST (r = -0.59, p < 0.01), and desired TIB (r = 0.44, p < 0.01). Linear regression analysis showed that the DBST could be predicted by insomnia severity (β=0.14, p = 0.035, adjusted R2=0.03, F=3.21, p = 0.004). Insomnia severity was predicted by preoccupation with sleep (β=0.64, p < 0.001), dysfunctional beliefs about sleep (β=0.06, p < 0.001), depression (β=0.23, p < 0.001), and DBST (β=0.32, p = 0.035). The DBST directly influenced insomnia severity, and this association was shown to be mediated by depression, dysfunctional beliefs and attitude about sleep, and preoccupation with sleepConclusionsThe DBST could be a possible new sleep index due to its relation with insomnia severity, depression, dysfunctional beliefs about sleep, or preoccupation with sleep. Further studies are needed to explore the consistency of the clinical sample.

Four Useful Concepts When Treating Patients With Insomnia: Possibility of Sleep Index-Based Cognitive Behavioral Therapy for Insomnia

“…The DBST index seems related to the dysfunctional beliefs about sleep. Our previous studies [11][12][13] showed a correlation between the DBST index and rating scales for measuring dysfunctional beliefs about sleep. Although the severity of insomnia is the most powerful predictor of the DBST index, dysfunctional beliefs about sleep may also have an effect on it.…”

“…The desired TIB can be determined by asking, "From what time to what time do you wish to sleep?" The DBST index is calculated as "desired TIB hours-desired hours of TST" [12]. According to a previous report [11], the DBST index is one of the components predicting insomnia severity in the general population, along with depression, preoccupation with sleep, and dysfunctional beliefs about sleep.…”

“…PTW[19] Duration from administration of sleeping pills to wake up time 7-8 hours WTB[10] Duration from wake-up time to bedtime 16-17 hours WTS[10] Duration from wake-up time to sleep onset time 16-17 hours DBST index[12] Discrepancy between desired TIB and desired TST Almost 0…”

Discrepancy between Desired Time in Bed and Desired Total Sleep Time in Patients with Cancer: The DBST Index and the Relationship with Insomnia Severity or Sleep Onset Latency

“…We previously reported that the DBST index may be an index for insomnia severity [14,15]. Among the general population [14], the DBST index was significantly correlated with insomnia severity or preoccupation with sleep.…”

“…The DBST index refers to the discrepancy between one's desired total hours in bed and one's desired hours of total sleep [14,15]. One of the most popular misbeliefs of patients with insomnia is that the longer the sleeping time, the better it is for health.…”