Nicole Lovato

A meta-analysis and model of the relationship between sleep and depression in adolescents: Recommendations for future research and clinical practice

The purpose of this review was to quantify the strength of evidence for a directional relationship between sleep disturbance and depression in adolescents. A literature search was conducted to identify research investigating the relationship between sleep disturbance and depression in adolescent samples (12-20 y). Twenty-three studies were identified; 13 explored associations between depression and sleep disturbance; seven examined the prospective role of sleep disturbance in the development of depression; and three investigated the role of adolescent depression in the development of subsequent sleep disturbance. Average weighted mean differences in sleep/depression-related outcome variables were calculated between adolescents with depression, and non-clinical adolescents, or those in remission. Adolescents with depression experienced significantly more wakefulness in bed (sleep onset latency, wake after sleep onset, number of awakenings and sleep efficiency), lighter sleep (more stage 1), and reported more subjective sleep disturbance. Overall effect sizes from longitudinal and treatment studies suggest sleep disturbance acts as a precursor to the development of depression. At follow-up, depressed adolescents had significantly longer sleep onset, more wake after sleep onset, and lower sleep efficiency compared to adolescents who were non-clinical, or had undergone remission. Little support was found for a predictive role of depressive symptoms in the development of sleep disturbance. Based on these findings we propose a model to understand the development of depression from initial sleep disturbance, provide recommendations for clinicians and recommendations for future research.

Chronotype differences in circadian rhythms of temperature, melatonin, and sleepiness as measured in a modified constant routine protocol

Evening chronotypes typically have sleep patterns timed 2–3 hours later than morning chronotypes. Ambulatory studies have suggested that differences in the timing of underlying circadian rhythms as a cause of the sleep period differences. However, differences in endogenous circadian rhythms are best explored in laboratory protocols such as the constant routine. We used a 27-hour modified constant routine to measure the endogenous core temperature and melatonin circadian rhythms as well as subjective and objective sleepiness from hourly 15-minute sleep opportunities. Ten (8f) morning type individuals were compared with 12 (8f) evening types. All were young, healthy, good sleepers. The typical sleep onset, arising times, circadian phase markers for temperature and melatonin and objective sleepiness were all 2–3 hours later for the evening types than morning types. However, consistent with past studies the differences for the subjective sleepiness rhythms were much greater (5–9 hours). Therefore, the present study supports the important role of subjective alertness/sleepiness in determining the sleep period differences between morning and evening types and the possible vulnerability of evening types to delayed sleep phase disorder.

Does one hour of bright or short-wavelength filtered tablet screenlight have a meaningful effect on adolescents’ pre-bedtime alertness, sleep, and daytime functioning?

Electronic media use is prevalent among adolescent populations, as is the frequency of sleeplessness. One mechanism proposed for technology affecting adolescents’ sleep is the alerting effects from bright screens. Two explanations are provided. First, screens emit significant amounts of short-wavelength light (i.e. blue), which produces acute alertness and alters sleep timing. Second, later chronotypes are hypothesised to be hypersensitive to evening light. This study analysed the pre-sleep alertness (GO/NOGO task speed, accuracy; subjective sleepiness), sleep (sleep diary, polysomnography), and morning functioning of 16 healthy adolescents (M = 17.4 ± 1.9 yrs, 56% f) who used a bright tablet screen (80 lux), dim screen (1 lux) and a filtered short-wavelength screen (f.lux; 50 lux) for 1 hr before their usual bedtime in a within-subjects protocol. Chronotype was analysed as a continuous between-subjects factor; however, no significant interactions occurred. Significant effects occurred between bright and dim screens for GO/NOGO speed and accuracy. However, the magnitude of these differences was small (e.g. GO/NOGO speed = 23 ms, accuracy = 13%), suggesting minimal clinical significance. No significant effects were found for sleep onset latency, slow-rolling eye movements, or the number of SWS and REM minutes in the first two sleep cycles. Future independent studies are needed to test short (1 hr) vs longer (>2 hrs) screen usage to provide evidence for safe-to-harmful levels of screenlight exposure before adolescents’ usual bedtime.

The relationship between subjective and objective sleepiness and performance during a simulated night-shift with a nap countermeasure

The aim of the present study was to investigate the relationship between perceived and actual sleepiness and performance during a simulated night-shift that included a 30-min night-nap as an on-duty sleepiness countermeasure. Twenty-four healthy young adults (nine males, fifteen females) participated in a repeated measures design comprising two experimental conditions: no night-nap and 30-min night-nap. Both groups were given a 2-h prophylactic afternoon sleep opportunity (1500-1700 h). Measures of subjective sleepiness (Stanford Sleepiness Scale, Karolinska Sleepiness Scale and Visual Analogue Scale), objective sleepiness (sleep latency tests), objective performance (Symbol-Digit Substitution Task) and reaction time (Psychomotor Vigilance Task) were taken before the night-nap (0230 h) and at several intervals post-nap. Time-series correlation analyses indicated that subjective sleepiness was less correlated with objective sleepiness and objective performance when participants were given a 30-min night-nap. However subjective sleepiness and reaction time performance was strongly correlated in both conditions, and there was no significant difference between the nap and no-nap conditions. Consistent with previous research, results of the present study indicate that subjective and objective indicators of sleepiness and performance may not always correspond, and this relationship may be reduced by the inclusion of a night-nap.

Evaluation of a Brief Treatment Program of Cognitive Behavior Therapy for Insomnia in Older Adults

OBJECTIVE To evaluate the efficacy of a brief 4-w group-administered treatment program of cognitive behavior therapy for insomnia (CBT-I) for older adults with sleep maintenance insomnia. DESIGN Randomized controlled trial of CBT-I compared to waitlist control with comparisons at pretreatment, posttreatment, and 3-mo follow-up. SETTING Flinders University Sleep and Circadian Rhythm Research Laboratory, Adelaide, South Australia. PARTICIPANTS One-hundred eighteen adults with sleep maintenance insomnia (mean age = 63.76 y, standard deviation = 6.45 y, male = 55). INTERVENTIONS A 4-w, group-based treatment program of CBT-I including bedtime restriction therapy, sleep education, and cognitive restructuring. MEASUREMENTS Seven-day sleep diaries, actigraphy, and several self-report measures to assess perceived insomnia severity, daytime functioning, and confidence in and beliefs about sleep. RESULTS The brief group-administered CBT-I program produced improvements in the timing and quality of sleep including later bedtimes, earlier out-of-bed times, reduced wake after sleep onset, and improved sleep efficiency. Participants also reported a reduction of the Insomnia Severity Index, Flinders Fatigue Scale, Epworth Sleepiness Scale, Daytime Feeling and Functioning Scale, Sleep Anticipatory Anxiety Questionnaire, the Dysfunctional Beliefs and Attitudes Scale, and increased Sleep Self-Efficacy Scale. CONCLUSIONS The treatment program used in the current study has demonstrated potential for a brief, inexpensive, and effective treatment of sleep maintenance insomnia in the older adult population.

Delayed sleep phase disorder in an Australian school-based sample of adolescents.

STUDY OBJECTIVES To establish the extent to which the developmental changes in sleep timing experienced by Australian adolescents meet the International Classification of Sleep Disorders (ICSD-2) diagnostic criteria for delayed sleep phase disorder (DSPD), and whether adolescents with DSPD engage in poorer lifestyle choices, and are more impaired compared to good sleeping adolescents. METHODS Three-hundred seventy-four Australian adolescents (mean age 15.6 years, SD 1.0) participants completed a 7-day sleep diary, wore wrist actigraphy, and completed a battery of questionnaires to assess DSPD criteria. RESULTS The ICSD-2 criteria for DSPD were met by 1.1% (N = 4) of the adolescents sampled. The majority of adolescents (51.9%, N = 194) met one criterion, 14% (N = 52) of the adolescents met 2 criteria, while 33.2% (N = 124) did not fulfill any DSPD criteria. Despite having significantly delayed sleep timing, adolescents who met all criteria for DSPD reported similar lifestyle habits and daytime functioning. However, there were trends for greater alcohol and caffeine consumption, less sport participation, yet more time spent on extracurricular activities (i.e., learning to play a musical instruments for adolescents with DSPD. CONCLUSIONS Despite the majority of adolescents reporting DSPD symptoms, only a small minority met full diagnostic criteria. Adolescents with DSPD reported similar lifestyle habits and daytime functioning to those with some or no symptoms. Future investigations of non-school-attending DSPD adolescents are needed to confirm the trends for lifestyle behaviors found in the present study.

Trying to fall asleep while catastrophising: what sleep-disordered adolescents think and feel.

OBJECTIVE Catastrophising is a repetitive cognitive process related to sleep disturbance in adult insomnia patients. More recently catastrophising has been associated with increased sleep disturbances in community samples of children and adolescents, with this association mediated by anxiety and depression. However, there currently is no evidence of these processes outside of community samples; impeding our ability to draw clinical conclusions. Knowledge on such dysfunctional cognitive processes in adolescents experiencing sleep disturbance would be clinically beneficial in aetiology and intervention. Our research examined the link between catastrophising, anxiety, depression and sleep latency in a sample of sleep-disordered adolescents. We also explored specific catastrophising themes which may impact the sleep latency of these adolescents. METHOD Forty adolescents (age=15.1±1.5 years, 53% boys) diagnosed with delayed sleep phase disorder completed a 7-day sleep diary, along with measures of anxiety and depression and a catastrophising interview with a trained sleep therapist. RESULTS Several catastrophisation themes were generated, the most common concerning interpersonal and performance aspects of school. Bootstrapping analyses showed depression did not mediate the relationship between catastrophising and sleep; however, an indirect relationship was found between catastrophising, anticipatory anxiety, and sleep latency. CONCLUSION These findings have implications for the role of dysfunctional thinking in prolonging sleep onset for adolescents and providing a clinical framework for health professionals when assessing and treating adolescents with delayed sleep timing.

Nocturnal Melatonin Profiles in Patients with Delayed Sleep-Wake Phase Disorder and Control Sleepers

A significant delay in the timing of endogenous circadian rhythms has been associated with delayed sleep phase disorder (DSPD). More recently, other mechanisms have also been proposed to account for this disorder. To further explore the etiology of DSPD, the present study compared nocturnal melatonin profiles of 26 DSPD patients (18 males, 8 females; age, 21.73 ± 4.98 years) and 17 normally timed good sleepers (10 males, 7 females; age, 23.82 ± 5.23 years) in a time-free, dim-light (<10 lux) laboratory environment. A 30-h modified constant routine with alternating 20-min sleep opportunities and 40 min of enforced wakefulness was used to measure the endogenous melatonin circadian rhythm. Salivary melatonin was sampled half-hourly from 1820 h to 0020 h and then hourly from 0120 h to 1620 h. DSPD patients had significantly later timed melatonin profiles that were delayed by approximately 3 h compared to normal sleepers, and there were no notable differences in the relative duration of secretion between groups. However, melatonin secretion between dim-light melatonin onset (DLMO) and acrophase was less prominent in DSPD patients compared to good sleepers, who showed a more acute initial surge of melatonin following the DLMO. Although the regulatory role of melatonin is unknown, abnormal melatonin profiles have been linked to psychiatric and neurological disorders (e.g., major depression, obsessive compulsive disorder, Parkinson disease). These results therefore suggest that in addition to a delayed endogenous circadian rhythm, a diminished initial surge of melatonin secretion following DLMO may contribute to the etiology of DSPD.

The etiology of delayed sleep phase disorder

According to classification manuals for sleep disorders, nine disorders are directly related to biological clock timing misalignments. Of all, delayed sleep phase disorder (DSPD) is the most commonly diagnosed, predominantly affecting adolescents, young adults, and insomnia patients. It is a persistent inability to fall asleep at earlier, more desirable and socially conventional times, coupled with extreme difficulty awakening in the morning. Considerable evidence shows a delay in the circadian clock to be associated with DSPD. Therefore, treatments have mainly focused on advancing the biological clock and sleep timing through pharmacotherapy, phototherapy and behavioral therapies. The clinical evidence indicates that these treatments are efficacious, at least in the short term. However, follow up studies show frequent patient relapse, leading researchers to speculate that alternative etiologies may be contributing to sleep and circadian clock delays in DSPD. The aim of the present paper is to review and collate current literature related to DSPD etiology in order to outline gaps in current knowledge and suggest future research.

Working memory performance of older adults with insomnia

Older individuals suffering insomnia typically report declines in their cognitive performance beyond what they consider to be normal changes due to the aging process. Recent neuro‐imaging studies have demonstrated frontal lobe hypo‐activation among insomniac populations when compared with healthy, good sleepers. However, research is yet to confirm whether frontal lobe hypo‐activation translates into objective declines when performing tasks hypothesized to draw upon this brain region. This study aimed to investigate whether older insomnia sufferers demonstrate significantly impaired performance on a challenging working memory task when compared with age‐matched good sleepers. Forty‐nine older individuals (mean age = 69.43 years, SD = 4.83) suffering from sleep maintenance insomnia were compared with 49 age‐matched good sleepers. Cognitive performance was assessed using the Double Span Memory Task, a computer‐based working memory task that requires participants to indicate the names and/or spatial locations of increasingly longer sequences of visually presented objects. After controlling for general intelligence, the individuals suffering from insomnia did not perform differently when compared with the good sleepers on either the simpler or more cognitively demanding components of the task. Older individuals with insomnia did not display an observable impairment of working memory in this study relative to good sleepers. Despite the mixed results from previous research, this study adds weight to the absence of objective impairment in insomniacs, at least while performing short‐term demanding cognitive tasks.