SLEEP Articles

The Emerging Role of Hypocretin (Orexin-A) in the Developing Central Nervous System

Seeking Useful Biomarkers for the Quality and Effectiveness of Sleep

Insomnia Research Is Coming of Age

Maturation of Heart Rate and Blood Pressure Variability during Sleep in Term-Born Infants

Study Objectives:

Abnormal blood pressure control is implicated in the sudden infant death syndrome (SIDS). However, no data exist on normal development of blood pressure control during infancy. This study assessed maturation of autonomic control of blood pressure and heart rate during sleep within the first 6 months of life.

Participants:

Term infants (n = 31) were studied longitudinally at 2-4 weeks, 2-3 months, and 5-6 months postnatal age.

Interventions:

Infants underwent daytime polysomnography at each age studied. Blood pressure and heart rate were recorded during quiet (QS) and active (AS) sleep in undisturbed baseline and head-up tilt conditions.

Measurements and Results:

Autonomic control was assessed using spectral indices of blood pressure and heart rate variability (BPV and HRV) in ranges of low frequency (LF, reflecting sympathetic + parasympathetic activity) and high frequency (HF, parasympathetic activity), total power (LF+HF), and LF/HF ratio (sympathovagal balance).

With increasing postnatal age and predominantly during QS, HRV-LF, HRV-HF, and HRV total power increased, while HRV-LF/HF decreased. BPV-LF/HF also decreased with postnatal age. All changes were evident in both baseline and head-up tilt conditions. BPV-LF and BPV total power during tilts were markedly reduced in QS versus AS at each age.

Conclusions:

In sleeping infants, sympathetic vascular modulation of the circulation decreases with age, while parasympathetic control of heart rate is strengthened. These normative data will aid in the early identification of conditions where autonomic function is impaired, such as in SIDS.

Citation:

Yiallourou SR; Sands SA; Walker AM; Horne RSC. Maturation of heart rate and blood pressure variability during sleep in term-born infants. SLEEP 2012;35(2):177-186.

CSF Levels of Hypocretin-1 (Orexin-A) Peak during Early Infancy in Humans

Study Objectives:

Hypocretin (orexin) is a unique neuropeptide involved in the consolidation of wakefulness and sleep. Although hypocretin-1 levels in the cerebrospinal fluid (CSF) are stable after infancy, how levels change in preterm and term human infants is unknown.

Design, Patients, and Setting:

Hypocretin-1 levels were measured in CSF samples, obtained from 284 preterm (25-37 gestational weeks) and full-term infants in the first 4 months of life and 35 older children (ages 0.5-13 years), in a tertiary hospital.

Measurements and Results:

Detailed clinical and laboratory data were collected for each of the 319 participants. Based on that data, 108 neurologically intact children were selected (95 infants [43 preterm and 52 term] and 13 older children). CSF hypocretin-1 was measured by direct radioimmunoassay. Hypocretin-1 levels at the first weeks of the 3rd embryonic trimester (gestational age [GA] 28-34 weeks) were 314 ± 65 pg/mL (n = 17). The levels linearly increased during the third trimester and early infancy (r = 0.6), peaking in infants of 2-4 months ages (476 ± 72 pg/mL; n = 16) and decreasing thereafter; hypocretin levels in 2- to 4-month-old infants were significantly higher than those in children 0.5-13 years old (353 ± 78 pg/mL, n = 13; P = 0.0001).

Conclusions:

The present findings indicate that in human infants, CSF hypocretin-1 increases during the third embryonic trimester and is highest at 4 months of life. Thereafter, and consistent with previously published results, hypocretin levels are lower and stable until the geriatric age. This pattern may reflect the role of hypocretin in the dramatic process of sleep and wakefulness consolidation that occurs during early infancy.

Citation:

Aran A; Shors I; Lin L; Mignot E; Schimmel MS. CSF levels of hypocretin-1 (orexin-A) peak during early infancy in humans. SLEEP 2012;35(2):187-191.

An Adaptive-Duration Version of the PVT Accurately Tracks Changes in Psychomotor Vigilance Induced by Sleep Restriction

Study Objectives:

The Psychomotor Vigilance Test (PVT) is a widely used assay of behavioral alertness sensitive to the effects of sleep loss and circadian misalignment. The standard 10-minute duration of the PVT is often considered impractical for operational or clinical environments. Therefore, we developed and validated an adaptive-duration version of the PVT (PVT-A) that stops sampling once it has gathered enough information to correctly classify PVT performance.

Design:

Repeated-measures experiments involving 10-minute PVT assessments every 2 hours across both acute total sleep deprivation (TSD) and 5 days of chronic partial sleep deprivation (PSD).

Setting:

Controlled laboratory environment.

Participants:

Seventy-four healthy subjects (34 women), aged 22 to 45 years.

Interventions:

A TSD experiment involving 33 hours awake (n = 31 subjects), and a PSD experiment involving 5 nights of 4 hours time in bed (n = 43 subjects).

Measurements and Results:

The PVT-A algorithm was trained with 527 TSD test bouts and validated with 880 PSD test bouts. Based on our primary outcome measure “number of lapses (response times ≥ 500 ms) plus false starts (premature responses or response times < 100 ms),” 10-minute PVT performance was classified into high (≤ 5 lapses and false starts), medium (> 5 and ≤ 16 lapses and false starts), or low (> 16 lapses and false starts). The decision threshold for PVT-A termination was set so that at least 95% of training data-set tests were classified correctly and no test was classified incorrectly across 2 performance categories (i.e., high as low or low as high), resulting in an average test duration of 6.0 minutes (SD 2.4 min). In the validation data set, 95.7% of test bouts were correctly classified, and there were no incorrect classifications across 2 categories. Agreement corrected for chance was excellent (κ = 0.92). Across the 3 performance categories, sensitivity averaged 93.7% (range 87.2%-100%), and specificity averaged 96.8% (range 91.6%-99.9%). Test duration averaged 6.4 minutes (SD 1.7 min), with a minimum of 27 seconds.

Conclusions:

We developed and validated a highly accurate, sensitive, and specific adaptive-duration version of the 10-minute PVT. Test duration of the adaptive PVT averaged less than 6.5 minutes, with 60 tests (4.3%) terminating after less than 2 minutes, increasing the practicability of the test in operational and clinical settings. The adaptive-duration strategy may be superior to a simple reduction of PVT duration in which the fixed test duration may be too short to identify subjects with moderate impairment (showing deficits only later during the test) but unnecessarily long for those who are either fully alert or severely impaired.

Citation:

Basner M; Dinges DF. An adaptive-duration version of the PVT accurately tracks changes in psychomotor vigilance induced by sleep restriction. SLEEP 2012;35(2):193-202.

Respiratory Cycle-Related EEG Changes: Response to CPAP

Study Objectives:

Respiratory cycle-related EEG changes (RCREC) quantify statistically significant synchrony between respiratory cycles and EEG spectral power, vary to some extent with work of breathing, and may help to predict sleepiness in patients with obstructive sleep apnea. This study was designed to assess the acute response of RCREC to relief of upper airway obstruction by positive airway pressure (PAP).

Design:

Comparison of RCREC between baseline diagnostic polysomnograms and PAP titration studies.

Setting:

Accredited academic sleep disorders center.

Patients:

Fifty adults referred for suspected sleep disordered breathing.

Interventions:

For each recording, the RCREC in specific physiologic EEG frequency ranges were computed as previously described for the last 3 h of sleep not occupied by apneic events.

Results:

The sample included 27 women; mean age was 47 ± 11 (SD) years; and median respiratory disturbance index at baseline was 24 (inter-quartile range 15-43). Decrements in RCREC, from baseline to PAP titration, reached 43%, 24%, 14%, 22%, and 31% for delta (P = 0.0004), theta (P = 0.01), alpha (P = 0.10), sigma (P = 0.08), and beta (P = 0.01) EEG frequency ranges, respectively. Within each specific sleep stage, these reductions from baseline to PAP studies in synchrony between EEG power and respiratory cycles still reached significance (P < 0.05) for one or more EEG frequency ranges and for all frequency ranges during REM sleep.

Conclusions:

RCREC tends to diminish acutely with alleviation of upper airway obstruction by PAP. These data in combination with previous observations support the hypothesis that RCREC reflect numerous, subtle, brief, but consequential inspiratory microarousals.

Citation:

Chervin RD; Shelgikar AV; Burns JW. Respiratory cycle-related EEG changes: response to CPAP. SLEEP 2012;35(2):203-209.

Switch-Task Performance in Rats Is Disturbed by 12 h of Sleep Deprivation But Not by 12 h of Sleep Fragmentation

Study Objectives:

Task-switching is an executive function involving the prefrontal cortex. Switching temporarily attenuates the speed and/or accuracy of performance, phenomena referred to as switch costs. In accordance with the idea that prefrontal function is particularly sensitive to sleep loss, switch-costs increase during prolonged waking in humans. It has been difficult to investigate the underlying neurobiological mechanisms because of the lack of a suitable animal model. Here, we introduce the first switch-task for rats and report the effects of sleep deprivation and inactivation of the medial prefrontal cortex.

Design:

Rats were trained to repeatedly switch between 2 stimulus-response associations, indicated by the presentation of a visual or an auditory stimulus. These stimulus-response associations were offered in blocks, and performance was compared for the first and fifth trials of each block. Performance was tested after exposure to 12 h of total sleep deprivation, sleep fragmentation, and their respective movement control conditions. Finally, it was tested after pharmacological inactivation of the medial prefrontal cortex.

Settings:

Controlled laboratory settings.

Participants:

15 male Wistar rats.

Measurements & Results:

Both accuracy and latency showed switch-costs at baseline. Twelve hours of total sleep deprivation, but not sleep fragmentation, impaired accuracy selectively on the switch-trials. Inactivation of the medial prefrontal cortex by local neuronal inactivation resulted in an overall decrease in accuracy.

Conclusions:

We developed and validated a switch-task that is sensitive to sleep deprivation. This introduces the possibility for in-depth investigations on the neurobiological mechanisms underlying executive impairments after sleep disturbance in a rat model.

Citation:

Leenaars CHC; Joosten RNJMA; Zwart A; Sandberg H; Ruimschotel E; Hanegraaf MAJ; Dematteis M; Feenstra MGP; van Someren EJW. Switch-task performance in rats is disturbed by 12 h of sleep deprivation but not by 12 h of sleep fragmentation. SLEEP 2012;35(2):211-221.

Free Recall of Word Lists under Total Sleep Deprivation and after Recovery Sleep

Study Objectives:

One task that has been used to assess memory effects of prior total sleep deprivation (TSD) is the immediate free recall of word lists; however, results have been mixed. A possible explanation for this is task impurity, since recall of words from different serial positions reflects use of distinct types of memory (last words: short-term memory; first and intermediate words: episodic memory). Here we studied the effects of 2 nights of TSD on immediate free recall of semantically unrelated word lists considering the serial position curve.

Design:

Random allocation to a 2-night TSD protocol followed by one night of recovery sleep or to a control group.

Setting:

Study conducted under continuous behavioral monitoring.

Participants:

24 young, healthy male volunteers.

Intervention:

2 nights of total sleep deprivation (TSD) and one night of recovery sleep.

Measurements and Results:

Participants were shown five 15 unrelated word-lists at baseline, after one and 2 nights of TSD, and after one night of recovery sleep. We also investigated the development of recall strategies (learning) and susceptibility to interference from previous lists. No free recall impairment occurred during TSD, irrespective of serial position. Interference was unchanged. Both groups developed recall strategies, but task learning occurred earlier in controls and was evident in the TSD group only after sleep recovery.

Conclusion:

Prior TSD spared episodic memory, short-term phonological memory, and interference, allowed the development of recall strategies, but may have decreased the advantage of using these strategies, which returned to normal after recovery sleep.

Citation:

Zanini GAV; Tufik S; Andersen ML; da Silva RCM; Bueno OFA; Rodrigues CC; Pompéia S. Free recall of word lists under total sleep deprivation and after recovery sleep. SLEEP 2012;35(2):223-230.

Glucose Tolerance in Patients with Narcolepsy

Study Objectives:

Obesity is a common feature of narcolepsy. In addition, an increased occurrence of non-insulin dependent diabetes has been reported. So far, it is not known whether glucose metabolism in narcolepsy is disturbed due to, or independently of obesity.

Design:

Case-control study.

Setting:

Sleep medicine clinic at a research institute.

Patients:

We studied 17 patients with narcolepsy/cataplexy compared to 17 healthy controls matched for age, sex, and body mass index (BMI).

Interventions:

A 75-g oral glucose tolerance test was performed.

Measurements:

Glucose tolerance was determined by computing plasma glucose curve following oral glucose challenge for 240 minutes; insulin sensitivity and insulin secretion by homeostasis model assessment and minimal model analysis.

Results:

Standard outcome measures and indices of the oral glucose tolerance test did not differ between the patient group and the group of control subjects.

Conclusions:

In this study, no clinically relevant pathologic findings in the glucose metabolism of narcoleptic patients compared to weight matched controls were found. Thus, narcolepsy is unlikely to be a risk factor per se for impaired glucose tolerance or diabetes.

Citation:

Beitinger PA; Fulda S; Dalal MA; Wehrle R; Keckeis M; Wetter TC; Han F; Pollmächer T; Schuld A. Glucose tolerance in patients with narcolepsy. SLEEP 2012;35(2):231-236.

The Longitudinal Relationship between Fatigue and Sleep in Breast Cancer Patients Undergoing Chemotherapy

Study Objective:

Fatigue and sleep disturbances are two of the most common and distressing symptoms of cancer patients. A relationship between the two symptoms was reported in symptom cluster studies; however, only subjective measurements of sleep were examined and most studies were cross-sectional. In this study of women with breast cancer undergoing chemotherapy, we explored the longitudinal relationship between fatigue and sleep measured both subjectively and objectively.

Design:

Prospective study. Data were collected at 7 time points: before (baseline) and during the 3 weeks of cycle 1 and cycle 4 chemotherapy.

Participants:

Ninety-seven women with newly diagnosed stage I-III breast cancer who were scheduled to receive at least four 3-week cycles of chemotherapy.

Measurement and Results:

Objective sleep parameters were measured with an Actillume actigraph (Ambulatory Monitoring Inc.). Subjective sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI). Fatigue was assessed with the Multidimensional Fatigue Symptom Inventory-Short Form (MFSI-SF). Fatigue became worse during both cycles of chemotherapy (P-values < 0.01). Subjective sleep quality was poor at baseline and remained unchanged throughout treatment. Objective nighttime and daytime total sleep time increased compared to baseline during the treatment administration week of both cycles; daytime total wake time decreased during the treatment week of both cycles and during the last 2 week of cycle 4. Mixed model results revealed that fatigue was positively associated with total PSQI scores and with objective measures of total nap time, and negatively associated with total wake time during the day (all P-values < 0.01).

Conclusion:

Fatigue was significantly associated with subjective reports of poor sleep and objective measures of daytime sleepiness, but not with nocturnal sleep as measured with actigraphy. This relationship between fatigue and sleep warrants further studies to explore their possible common underlying etiology.

Citation:

Liu L; Rissling M; Natarajan L; Fiorentino L; Mills PJ; Dimsdale JE; Sadler GR; Parker BA; Ancoli-Israel S. The longitudinal relationship between fatigue and sleep in breast cancer patients undergoing chemotherapy. SLEEP 2012;35(2):237-245.

Sleep in Spousal Alzheimer Caregivers: A Longitudinal Study with a Focus on the Effects of Major Patient Transitions on Sleep

Study Objectives:

Findings on sleep disturbances in family dementia caregivers are conflicting. We studied the longitudinal effects of dementia caregiving and major transitions in the caregiving situation on caregivers' sleep and the effect of moderating variables.

Design and Setting:

Community-based longitudinal study with assessments about once a year for up to three years.

Participants:

A sample of 109 elderly spousal Alzheimer caregivers and 48 non-caregiving age- and gender-matched controls.

Measurements and Results:

Random regression models with fixed and time-variant effects for covariates known to affect sleep were used to evaluate changes in the Pittsburgh Sleep Quality Index (PSQI) and in four actigraphy measures over time in relation to caregiving status and transitions (i.e., nursing home placement or death of the Alzheimer disease spouse). Multivariate-adjusted sleep characteristics did not significantly differ between caregivers and non-caregivers over time. Spousal death increased caregivers' nighttime wake after sleep onset (WASO) by 23 min (P = 0.002) and daytime total sleep time (TST) by 29 min (P = 0.003), while nighttime sleep percent decreased by 3.2% (P = 0.009) and nighttime TST did not change. Placement of the spouse had no significant effect on caregivers' sleep. Older age, male gender, role overload, depressive symptoms, and proinflammatory cytokines variously emerged as significant moderators of the relationships between caregiving and transitions with poor subjective and objective sleep.

Conclusions:

Alzheimer caregivers and non-caregiving controls had similar trajectories of sleep. However, there may be subgroups of caregivers who are vulnerable to develop sleep disturbances, including those whose spouses have died.

Citation:

von Känel R; Mausbach BT; Ancoli-Israel S; Dimsdale JE; Mills PJ; Patterson TL; Ziegler MG; Roepke SK; Chattillion EA; Allison M; Grant I. Sleep in spousal alzheimer caregivers: a longitudinal study with a focus on the effects of major patient transitions on sleep. SLEEP 2012;35(2):247-255.

Daily Sleep and Fatigue Characteristics in Nulliparous Women during the Third Trimester of Pregnancy

Objectives:

To examine the association among nighttime sleep and daytime napping behaviors, depressive symptoms, and perception of fatigue in pregnant women.

Design:

A prospective descriptive study with within-subject design.

Setting:

A university-affiliated hospital and participants' home environments.

Participants:

Thirty-eight third trimester nulliparous women completed sleep and depressive symptom questionnaires, wore a wrist actigraphy monitor for 7 consecutive days, and kept a concurrent diary reporting naps and rating their level of fatigue using a 0-10 visual analogue scale each morning, midday, afternoon, and evening. A generalized estimating equation regression model was applied to evaluate the time-dependent association.

Interventions:

N/A.

Measurements and Results:

Mean duration of total nighttime sleep by actigraphy was 386.3 ± 60.7 min, with 11 (28.9%) women having an average total nighttime sleep < 6 h. Nineteen women (50%) napped > 3 days, and only 2 women did not nap over the entire week. Antecedent night sleep duration had a significant inverse association with morning (P = 0.022) and afternoon fatigue (P = 0.009) of the subsequent day. Self-reported naps were significantly associated with midday fatigue (P = 0.003). More depressive symptoms predicted more severe fatigue throughout the day.

Conclusions:

Results suggest that interventions designed to increase sleep duration and decrease depressive symptoms have the potential to prevent, ameliorate, or reduce fatigue in pregnant women. Depressive symptoms during pregnancy likely share some psychological and behavioral tendencies with fatigue and/or sleep disturbance which may complicate the evaluation of intervention effect.

Citation:

Tsai SY; Lin JW; Kuo LT; Thomas KA. Daily sleep and fatigue characteristics in nulliparous women during the third trimester of pregnancy. SLEEP 2012;35(2):257-262.

The Supraglottic Effect of a Reduction in Expiratory Mask Pressure During Continuous Positive Airway Pressure

Study Objectives:

Patients with obstructive sleep apnea may have difficulty exhaling against positive pressure, hence limiting their acceptance of continuous positive airway pressure (CPAP). C-Flex is designed to improve comfort by reducing pressure in the mask during expiration proportionally to expiratory airflow (3 settings correspond to increasing pressure changes). When patients use CPAP, nasal resistance determines how much higher supraglottic pressure is than mask pressure. We hypothesized that increased nasal resistance results in increased expiratory supraglottic pressure swings that could be mitigated by the effects of C-Flex on mask pressure.

Design:

Cohort study.

Setting:

Sleep center.

Participants:

Seventeen patients with obstructive sleep apnea/hypopnea syndrome and a mechanical model of the upper airway.

Interventions:

In patients on fixed CPAP, CPAP with different C-Flex levels was applied multiple times during the night. In the model, 2 different respiratory patterns and resistances were tested.

Measurements and Results:

Airflow, expiratory mask, and supraglottic pressures were measured on CPAP and on C-Flex. Swings in pressure during expiration were determined. On CPAP, higher nasal resistance produced greater expiratory pressure swings in the supraglottis in the patients and in the model, as expected. C-Flex 3 produced expiratory drops in mask pressure (range −0.03 to −2.49 cm H₂O) but mitigated the expira-tory pressure rise in the supraglottis only during a sinusoidal respiratory pattern in the model.

Conclusions:

Expiratory changes in mask pressure induced by C-Flex did not uniformly transmit to the supraglottis in either patients with obstructive sleep apnea on CPAP or in a mechanical model of the upper airway with fixed resistance. Data suggest that the observed lack of expiratory drop in supraglottic pressure swings is related to dynamics of the C-Flex algorithm.

Citation:

Masdeu MJ; Patel AV; Seelall V; Rapoport DM; Ayappa I. The supraglottic effect of a reduction in expiratory mask pressure during continuous positive airway pressure. SLEEP 2012;35(2):263-272.

Effects of a 3-Hour Sleep Delay on Sleep Homeostasis in Alcohol Dependent Adults

Objectives:

This study evaluated slow wave activity homeostatic response to a mild sleep challenge in alcohol-dependent adults compared to healthy controls.

Design:

Participants maintained a 23:00-06:00 schedule for 5 days verified by actigraphy and diary, followed by 3 nights in the lab: adaptation, baseline, and a sleep delay night with an 02:00-09:00 schedule.

Setting:

Sleep ' Chronophysiology laboratory.

Participants:

48 alcohol-dependent adults (39 men, 9 women) who were abstinent for at least 3 weeks and 16 healthy control adults (13 men, 3 women), 21-55 years of age participated in study.

Interventions:

N/A.

Measurements and Results:

Slow wave EEG activity (SWA) in consecutive NREM periods was compared between baseline and sleep delay nights and between AD and HC groups, using age and sex as statistical covariates. The AD group showed a blunted SWA response to sleep delay with significantly lower SWA power than the HC group. Exponential regression analyses confirmed lower asymptotic SWA with a slower decay rate over NREM sleep time in the AD group. Results were similar for raw SWA and %SWA on the delay night expressed relative to baseline SWA.

Conclusions:

Alcohol dependence is associated with impaired SWA regulation and a blunted response to a mild homeostatic sleep challenge.

Citation:

Armitage R; Hoffmann R; Conroy DA; Arnedt JT; Brower KJ. Effects of a 3-hour sleep delay on sleep homeostasis in alcohol dependent adults. SLEEP 2012;35(2):273-278.

A Closed Literature-Based Discovery Technique Finds a Mechanistic Link Between Hypogonadism and Diminished Sleep Quality in Aging Men

Study Objectives:

Sleep quality commonly diminishes with age, and, further, aging men often exhibit a wider range of sleep pathologies than women. We used a freely available, web-based discovery technique (Semantic MEDLINE) supported by semantic relationships to automatically extract information from MEDLINE titles and abstracts.

Design:

We assumed that testosterone is associated with sleep (the A-C relationship in the paradigm) and looked for a mechanism to explain this association (B explanatory link) as a potential or partial mechanism underpinning the etiology of eroded sleep quality in aging men.

Measurements and Results:

Review of full-text papers in critical nodes discovered in this manner resulted in the proposal that testosterone enhances sleep by inhibiting cortisol. Using this discovery method, we posit, and could confirm as a novel hypothesis, cortisol as part of a mechanistic link elucidating the observed correlation between decreased testosterone in aging men and diminished sleep quality.

Conclusions:

This approach is publically available and useful not only in this manner but also to generate from the literature alternative explanatory models for observed experimental results.

Citation:

Miller CM; Rindflesch TC; Fiszman M; Hristovski D; Shin D; Rosemblat G; Zhang H; Strohl KP. A closed literature-based discovery technique finds a mechanistic link between hypogonadism and diminished sleep quality in aging men. SLEEP 2012;35(2):279-285.

The Consensus Sleep Diary: Standardizing Prospective Sleep Self-Monitoring

Study Objectives:

To present an expert consensus, standardized, patient-informed sleep diary.

Methods and Results:

Sleep diaries from the original expert panel of 25 attendees of the Pittsburgh Assessment Conference¹ were collected and reviewed. A smaller subset of experts formed a committee and reviewed the compiled diaries. Items deemed essential were included in a Core sleep diary, and those deemed optional were retained for an expanded diary. Secondly, optional items would be available in other versions. A draft of the Core and optional versions along with a feedback questionnaire were sent to members of the Pittsburgh Assessment Conference. The feedback from the group was integrated and the diary drafts were subjected to 6 focus groups composed of good sleepers, people with insomnia, and people with sleep apnea. The data were summarized into themes and changes to the drafts were made in response to the focus groups. The resultant draft was evaluated by another focus group and subjected to lexile analyses. The lexile analyses suggested that the Core diary instructions are at a sixth-grade reading level and the Core diary was written at a third-grade reading level.

Conclusions:

The Consensus Sleep Diary was the result of collaborations with insomnia experts and potential users. The adoption of a standard sleep diary for insomnia will facilitate comparisons across studies and advance the field. The proposed diary is intended as a living document which still needs to be tested, refined, and validated.

Citation:

Carney CE; Buysse DJ; Ancoli-Israel S; Edinger JD; Krystal AD; Lichstein KL; Morin CM. The consensus sleep diary: standardizing prospective sleep self-monitoring. SLEEP 2012;35(2):287–302.