帕罗西汀治疗慢性失眠症的临床对照研究

目的：探索帕罗西汀在慢性失眠症的治疗中是否有效，并比较帕罗西汀与艾司唑仑治疗慢性失眠症的临床效果。方法：74名慢性失眠患者，随机分成2组，分别接受帕罗西汀与艾司唑仑治疗。采用匹兹堡睡眠质量指数(PSQI）及睡眠日记评定疗效。结果：治疗第8天，艾司唑仑组患者睡眠状况显著改善，而帕罗西汀组则无明显变化：治疗第15天时．帕罗西汀组患者睡眠状况显著改善，睡眠各项指标与治疗前及艾司唑仑组相比，差异具有统计学意义，而艾司唑仑组患者的睡眠状况又恢复到治疗前的水平：治疗结束时及治疗结束后3个月，帕罗西汀组患者的睡眠状况依然好于治疗前及艾司唑仑组，差异具有统计学意义。结论：帕罗西汀可以有效治疗慢性失眠症，远期效果好于苯二氮Zhuo类药物艾司唑仑。     

改良森田疗法与安眠药物对慢性原发性失眠症治疗效果对比分析

目的比较改良森田疗法和安眠药物对慢性原发性失眠症的治疗效果。方法将91例慢性原发性失眠症患者分成3组,A组单纯药物治疗;B组单纯改良森田治疗;C组为安眠药物合并改良森田疗法治疗,疗程12周。于治疗前后分别用匹兹堡睡眠质量指数（PSQ I）、焦虑自评量表（SAS）、抑郁自评量表（SDS）评定疗效,半年后再随访。结果安眠药物治疗失眠起效快,短期效果好;森田疗法不但改善患者睡眠质量,而且能改善与失眠相关的心理状态,远期疗效较好且优于联合组。结论改良森田疗法是治疗慢性原发性失眠症的较好方法。     

认知行为疗法与佐匹克隆治疗失眠症对照研究

目的 观察认知行为疗法(CBT)和服用佐匹克隆治疗对失眠症患者的睡眠质量和心理健康水平疗效.方法 选择符合CCMD-3的失眠症患者64例,随机分为药物组、认知行为治疗组,共治疗8周,治疗前后分别测试两组的睡眠质量和心理健康水平.结果 治疗结束后,比较药物组、CBT组疗效,SCL- 90躯体化(t=2.683,P＜0...     

认知疗法治疗慢性失眠症的对照研究

目的探讨认知疗法对慢性失眠症的治疗效果。方法将睡眠障碍专科门诊的93例慢性失眠症患者,随机分为试验组47例和对照组46例,试验组采用认知治疗加药物治疗,对照组采用单纯药物治疗,疗程均为8周。治疗前后采用睡眠个人信念和态度量表(DBAS)及匹兹堡睡眠质量指数量表(PSQI)测评。结果慢性失眠症患者普遍存在认知偏差,通过认知治疗,患者的睡眠数量和质量均有改善。结论认知治疗能改变慢性失眠症患者对睡眠的错误认知,提高治疗效果。     

认知行为疗法对失眠症患者睡眠和生活质量的影响

目的探讨认知行为疗法对失眠症患者睡眠质量和生活质量的影响。方法39例失眠症患者随机分成研究组和对照组，研究组给予安眠药物与认知行为疗法治疗，对照组单纯药物治疗。匹兹堡睡眠质量指数（PSQI）评价睡眠质量，总体幸福感量表（GWB）评价生活质量。结果匹兹堡睡眠质量（PSQJ）总分、睡眠质量、入睡时间、睡眠时间、睡眠效率、睡眠障碍、催眠药物使用、日间功能因子分．以及总体幸福感（GWB）总分治疗前后均有显著性差异（P〈0．05）；在第三周末，研究组PSQI及GWB总分均优于对照组。结论认知行为疗法对失眠症患者有良好的疗效，同时提高患者生活质量。     

失眠症者睡眠的主观评估和多导睡眠图对比分析

目的：探讨失眠症患者对睡眠评估的心理特征。方法：应用多导睡眠图对５０例失眠症患者进行整夜睡眠描记,次日早晨起床后询问夜间睡眠情况,并与２２名正常人进行对比分析。结果：与对照组比较、失眠症组睡眠潜伏期长,睡眠时间减少,睡眠效率低（Ｐ〈０．０１）;失眠症主观评估的睡眠潜伏期,总睡眠时间和睡眠效率与多导睡眠图结果比较具有显著不一致（Ｐ〈０．０５￣０．０１）。结论：失眠症组不但睡眠质量低于正常人,而且有着     

认知行为疗法对失眠症疗效的影响

目的观察认知行为疗法（CBT）对失眠症患者睡眠质量和心理健康水平疗效的影响。方法选择符合CCMD-3的失眠症患者72例,药物组36例,服用佐匹克隆,联合治疗组36例,以佐匹克隆合并认知行为疗法治疗,共治疗8周,治疗前后分别用症状自评量表（SCL-90）评价心理健康水平,用匹兹堡睡眠质量指数（PSQI）评定临床疗效。结果治疗结束后,比较药物组和联合治疗组SCL-90评分躯体化（t=2.682,P〈0.01）、人际关系敏感（t=2.685,P〈0.01）、强迫症状（t=2.983,P〈0.01）、抑郁（t=2.045,P〈0.05）、焦虑（t=2.650,P〈0.01）,联合治疗组评分明显低于药物组;匹兹堡睡眠质量（t=2.366,P〈0.05）、入睡时间（t=2.398,P〈0.05）、睡眠效率（t=2.176,P〈0.05）、睡眠药物（t=2.060,P〈0.05）,各因子联合治疗组得分明显低于药物组。结论认知行为疗法可提高失眠症患者的心理健康水平,改善患者睡眠质量和情绪症状,减少药物不良反应。     

短睡眠者与失眠症患者的睡眠生理和心理活动差别分析

目的：比较短睡眠者,失眠症患者和睡眠正常者的睡眠生理及心理活动特点,并对失眠症状的影响因素进行分析。方法：对三组对试选用MMPI人格评定,昼间心理生理唤醒实验,人睡前情评定及多导睡眠图整夜睡眠描记。结果：短睡眠组的睡眠潜伏期长于失眠症组,睡眠总时间和睡眠效率与失眠症组无显著差别;但醒起时间,醒觉时间和日间功能障碍分显著低于失眠症组,与睡眠正常组无显著性判别,MMPI评定,短睡眠组在疑病,抑郁,癔病及精神衰弱项目分低于失眠症组,与睡眠正常组无显著性差别,社会内向性项目分低于失眠症组和睡眠正常组,轻躁狂项目分高于失眠症组和睡眠正常组,短睡眠组的夜间人睡前焦虑水平低,白天心理生理唤醒值与睡眠生理指标的相关系数低于失眠症组。结论：短睡眠者的睡眠潜伏期长,睡眠总时间短,但睡眠质量好,人格特征,夜间情绪水平接近正常人。     

主诉失眠的门诊就诊者主客观评估的睡眠质量与生命质量

目的:失眠者的主观睡眠感与实际睡眠情况常有不一致的现象,本研究通过探讨以失眠为主诉的门诊就诊者睡眠质量的主观、客观评估指标与生命质量的相关性,为临床制定失眠的整体治疗方案提供参考依据。方法:连续收集64例以失眠为主诉的接受多导睡眠图(PSG)检查的门诊患者的资料,用匹兹堡睡眠质量指数(PSQI)评估主观睡眠质量,SF-36健康调查量表评估生命质量,用贝克抑郁问卷(BDI)、贝克焦虑问卷(BAI)评估情绪状态。以17例正常人的PSG数据作为客观睡眠质量的基础对照。结果:本组失眠就诊者90%主观评价睡眠质量差,其PSG指标中与正常对照相比睡眠潜伏期延长、清醒次数增加、睡眠效率降低、快动眼睡眠潜伏期延长(均P<0.05)。失眠就诊者PSQI总分与SF-36生理健康总分呈负相关(r=-0.25,P<0.05),但以BDI、BAI分作为控制变量进行偏相关分析显示,PSQI总分及各因子分与SF-36生理健康和心理健康总分相关性无统计学意义;PSG主要指标与SF-36生理健康和心理健康总分相关性无统计学意义。结论:本研究显示失眠者主观感受的睡眠质量更可能与生命质量相关,但与失眠相关的抑郁、焦虑情绪可能起到主要作用,这提示失眠治疗中应重视改善患者的主观睡眠质量,以及识别和处理情绪问题。     

中风后抑郁患者的多道睡眠图研究

目的：探讨多道睡眠图（PSG）指标对中风后抑郁（PSD）的诊断价值。方法：30例研究对象分为3组进行多道睡眠图（PSG）检查并分析其结果：病例组为10例PSD患者，根据DSM-IV诊断标准确诊；对照组为10例中风后抑郁的患者；正常组为年龄、性别匹配的健康者。结果：与对照组、正常组比较，病例组睡眠结构发生明显变化，表现为睡眠潜伏期缩短，RSM-NREM周期次数增加；RER潜伏期缩短；REM活动度、强度、密度增加；S1阶段睡眠增加，S2和S3 4阶段睡眠减少。总睡眠时间、慢波睡眠时间比正常组少，但与对照组之间无差异。三组之间觉醒时间及睡眠效率无明显差异。结论：PSD患者存在PSG指标变化，这些改变可能有助于PSD的诊断参考。     

Comparison of sleep condition and sleep-related psychological activity after cognitive-behavior and pharmacological therapy for chronic insomnia

BACKGROUND: Previous studies of insomnia focused mainly on the improvement of sleep condition and ignored the effects of sleep-related psychological activity and daytime function after pharmacological and behavioral treatments. We compared the clinical effects of both therapies on sleep condition, sleep-related psychological activity and daytime function in chronic insomnia. METHODS: Seventy-one patients with chronic insomnia were randomly divided into 4 groups and either received cognitive-behavior therapy (CBT, n = 19), pharmacological therapy (PCT, n = 17), CBT plus medication (Combined, n = 18) or placebo (n = 17). The treatments lasted for 8 weeks with follow-ups conducted at 3 and 8 months. On the day after treatment ended, all patients were assessed using a polysomnogram (PSG), a sleep diary and a psychological assessment. RESULTS: The three active treatments were more effective than placebo at the time the treatments were completed. Subjective sleep-onset latency, sleep efficacy and total sleep time were better in the PCT group than in the CBT group. At the 3-month follow-up, subjective and objective sleep-onset latency, sleep efficacy and total sleep time were better in the CBT group than in both the PCT and the Combined group. At the 8-month follow-up, the CBT group showed a steady comfortable sleep state, while the PCT and Combined groups were gradually returning to the pre-treatment condition. The Combined group showed a variable long-term effect. On the other hand, pre-sleep arousal at nighttime, dysfunctional beliefs about sleep as well as daytime functioning in the CBT group not only improved, but was better than in the other active treatment groups. CONCLUSION: Medication and Combined therapy produced a short-term effect on chronic insomnia while CBT had a long-term effect of improved sleep-related psychological activity and daytime functioning.     

Nonpharmacologic treatment of chronic insomnia. An American Academy of Sleep Medicine review

This paper reviews the evidence regarding the efficacy of nonpharmacological treatments for primary chronic insomnia. It is based on a review of 48 clinical trials and two meta-analyses conducted by a task force appointed by the American Academy of Sleep Medicine to develop practice parameters on non-drug therapies for the clinical management of insomnia. The findings indicate that nonpharmacological therapies produce reliable and durable changes in several sleep parameters of chronic insomnia sufferers. The data indicate that between 70% and 80% of patients treated with nonpharmacological interventions benefit from treatment. For the typical patient with persistent primary insomnia, treatment is likely to reduce the main target symptoms of sleep onset latency and/or wake time after sleep onset below or near the 30-min criterion initially used to define insomnia severity. Sleep duration is also increased by a modest 30 minutes and sleep quality and patient's satisfaction with sleep patterns are significantly enhanced. Sleep improvements achieved with these behavioral interventions are sustained for at least 6 months after treatment completion. However, there is no clear evidence that improved sleep leads to meaningful changes in daytime well-being or performance. Three treatments meet the American Psychological Association (APA) criteria for empirically-supported psychological treatments for insomnia: Stimulus control, progressive muscle relaxation, and paradoxical intention; and three additional treatments meet APA criteria for probably efficacious treatments: Sleep restriction, biofeedback, and multifaceted cognitive-behavior therapy. Additional outcome research is needed to examine the effectiveness of treatment when it is implemented in clinical settings (primary care, family practice), by non-sleep specialists, and with insomnia patients presenting medical or psychiatric comorbidity.     

Efficacy and safety of as-needed, post bedtime dosing with indiplon in insomnia patients with chronic difficulty maintaining sleep

OBJECTIVE: To evaluate the efficacy and tolerability of immediate release indiplon capsules in patients with chronic insomnia using an "as-needed" dosing strategy in response to difficulty falling back to sleep following a middle of the night, nocturnal awakening. METHODS: Adult outpatients (N=264; 71% female; age, 46 years) who met DSM-IV criteria for primary insomnia, with average total sleep time (TST) < 6.5 hours and >8 nights in the past month with nocturnal awakenings, were randomized to 4 weeks of double-blind treatment with 10 mg or 20 mg indiplon capsules, or placebo. The primary endpoint was latency to sleep onset post-dosing after a middle of the night awakening (LSOpd). Secondary endpoints included patients' subjective assessment of total sleep time (sTSTpd). Next day residual effects were evaluated by a 100 mm Visual Analog Scale (VAS) rating of sleepiness. RESULTS: Both doses of indiplon significantly reduced LSOpd at all time-points. Compared to placebo (45.2 min), the 4-week least squares (LS) mean LSOpd was 36.5 min in the indiplon 10 mg group (P = 0.0023) and 34.4 min in the indiplon 20mg group (P < 0.0001). The 4-week LS mean sTSTpd was higher in the indiplon 10 mg group (253 min) and 20mg group (278 min) compared to placebo (229 min; P < 0.01 for both comparisons). There was no increase observed in VAS ratings of next-day sleepiness for either dose of indiplon when compared to placebo. Indiplon was well-tolerated at both doses. CONCLUSIONS: Patients with chronic insomnia with nocturnal awakenings achieved significant and sustained improvement in sleep parameters while utilizing an as-needed post bedtime dosing strategy with indiplon capsules. Indiplon was well-tolerated, with no self-rated, next-day residual effects.     

Valerian-hops combination and diphenhydramine for treating insomnia: a randomized placebo-controlled clinical trial

CONTEXT: Insomnia is a prevalent health complaint associated with daytime impairments, reduced quality of life, and increased health-care costs. Although it is often self-treated with herbal and dietary supplements or with over-the-counter sleep aids, there is still little evidence on the efficacy and safety of those products. OBJECTIVE: To evaluate the efficacy and safety of a valerian-hops combination and diphenhydramine for the treatment of mild insomnia. DESIGN AND SETTING: Multicenter, randomized, placebo-controlled, parallel-group study conducted in 9 sleep disorders centers throughout the United States. PATIENTS: A total of 184 adults (110 women, 74 men; mean age of 44.3 years) with mild insomnia. INTERVENTIONS: (1) Two nightly tablets of standardized extracts of a valerian (187-mg native extracts; 5-8:1, methanol 45% m/m) and hops (41.9-mg native extracts; 7-10:1, methanol 45% m/m) combination for 28 days (n = 59), (2) placebo for 28 days (n = 65), or (3) 2 tablets of diphenhydramine (25 mg) for 14 days followed by placebo for 14 days (n = 60). OUTCOME MEASURES: Sleep parameters measured by daily diaries and polysomnography, clinical outcome ratings from patients and physicians, and quality of life measures. RESULTS: Modest improvements of subjective sleep parameters were obtained with both the valerian-hops combination and diphenhydramine, but few group comparisons with placebo reached statistical significance. Valerian produced slightly greater, though nonsignificant, reductions of sleep latency relative to placebo and diphenhydramine at the end of 14 days of treatment and greater reductions than placebo at the end of 28 days of treatment. Diphenhydramine produced significantly greater increases in sleep efficiency and a trend for increased total sleep time relative to placebo during the first 14 days of treatment. There was no significant group difference on any of the sleep continuity variables measured by polysomnography. In addition, there was no alteration of sleep stages 3-4 and rapid eye movement sleep with any of the treatments. Patients in the valerian and diphenhydramine groups rated their insomnia severity lower relative to placebo at the end of 14 days of treatment. Quality of life (Physical component) was significantly more improved in the valerian-hops group relative to the placebo group at the end of 28 days. There were no significant residual effects and no serious adverse events with either valerian or diphenhydramine and no rebound insomnia following their discontinuation. CONCLUSIONS: The findings show a modest hypnotic effect for a valerian-hops combination and diphenhydramine relative to placebo. Sleep improvements with a valerian-hops combination are associated with improved quality of life. Both treatments appear safe and did not produce rebound insomnia upon discontinuation during this study. Overall, these findings indicate that a valerian-hops combination and diphenhydramine might be useful adjuncts in the treatment of mild insomnia.     

Eight weeks of non-nightly use of zolpidem for primary insomnia

CONTEXT: Intermittent use (i.e., a few nights per week) of hypnotic medication is often recommended for the treatment of chronic insomnia despite an absence of efficacy and safety data using this regimen. STUDY OBJECTIVES: To evaluate the clinical efficacy and safety of intermittent pharmacotherapy for chronic insomnia. DESIGN AND SETTING: Randomized, double-blind, placebo-controlled, parallel groups, clinical trial at six sleep research sites. PATIENTS: One hundred-sixty-three (115 women, 48 men; mean age 44.1+ SE. 0.9 years), DSM-IV-defined primary insomnia patients were randomized, 134 patients completed the study. INTERVENTIONS: Eight weeks of treatment with either zolpidem 10 mg or placebo. Patients were instructed to take medication when they felt they needed it, but at least three and no more than five times per week. MAIN OUTCOME MEASURES: Investigator and Patient Global Ratings were the primary outcome variables. Secondary measures from daily questionnaires to assess efficacy, rebound insomnia and drug taking behavior. RESULTS: The Investigator's Global Rating indicated that intermittent use of zolpidem produced a significantly better therapeutic effect and significantly reduced insomnia severity throughout the 8-week study relative to placebo. Zolpidem was found to be effective in initiating and maintaining sleep on nights taken, as compared to placebo, based upon the Patient's Global Ratings and all subjective sleep variables. No evidence of rebound insomnia was found on nights that zolpidem was not taken. The number of nights a pill was taken did not differ between groups, nor did frequency of pill taking change in either group across the duration of the study. There were no significant effects of treatment upon quality of life or neurocognitive measures. CONCLUSIONS: Zolpidem 10 mg is effective in treating insomnia when used intermittently, without evidence of discontinuation effects or increased frequency of pill taking.     

Clinical Significance and Predictors of Treatment Response to Cognitive-Behavior Therapy for Insomnia Secondary to Chronic Pain

We examined individual responses to cognitive-behavior therapy for insomnia in 51 persons with chronic pain to determine the rate of clinically significant change and to identify predictors of successful treatment response. Outcome measures consisted of the Pittsburgh Sleep Quality Index (PSQI) and diary measures of sleep latency and sleep continuity. Using reliable change indices, 57% of participants were statistically improved on the PSQI after 7 weeks of treatment, but only 18% were considered fully recovered from their sleep problems. No demographic variables predicted treatment response but persons who reliably improved on the PSQI had a lower sleep self-efficacy at baseline. Improvers showed a significant increase in sleep self-efficacy ratings and a decrease in self-reported levels of distress and pain-related disability. These results suggest that patients with insomnia secondary to chronic medical conditions can be helped with cognitive-behavior therapy, although most individuals continue to have mild or subthreshold sleep problems at posttreatment.     

Psychological and behavioral treatment of insomnia:update of the recent evidence (1998-2004)

BACKGROUND: Recognition that psychological and behavioral factors play an important role in insomnia has led to increased interest in therapies targeting these factors. A review paper published in 1999 summarized the evidence regarding the efficacy of psychological and behavioral treatments for persistent insomnia. The present review provides an update of the evidence published since the original paper. As with the original paper, this review was conducted by a task force commissioned by the American Academy of Sleep Medicine in order to update its practice parameters on psychological and behavioral therapies for insomnia. METHODS: A systematic review was conducted on 37 treatment studies (N = 2246 subjects/patients) published between 1998 and 2004 inclusively and identified through Psyclnfo and Medline searches. Each study was systematically reviewed with a standard coding sheet and the following information was extracted: Study design, sample (number of participants, age, gender), diagnosis, type of treatments and controls, primary and secondary outcome measures, and main findings. Criteria for inclusion of a study were as follows: (a) the main sleep diagnosis was insomnia (primary or comorbid), (b) at least 1 treatment condition was psychological or behavioral in content, (c) the study design was a randomized controlled trial, a nonrandomized group design, a clinical case series or a single subject experimental design with a minimum of 10 subjects, and (d) the study included at least 1 of the following as dependent variables: sleep onset latency, number and/or duration of awakenings, total sleep time, sleep efficiency, or sleep quality. RESULTS: Psychological and behavioral therapies produced reliable changes in several sleep parameters of individuals with either primary insomnia or insomnia associated with medical and psychiatric disorders. Nine studies documented the benefits of insomnia treatment in older adults or for facilitating discontinuation of medication among chronic hypnotic users. Sleep improvements achieved with treatment were well sustained over time; however, with the exception of reduced psychological symptoms/ distress, there was limited evidence that improved sleep led to clinically meaningful changes in other indices of morbidity (e.g., daytime fatigue). Five treatments met criteria for empirically-supported psychological treatments for insomnia: Stimulus control therapy, relaxation, paradoxical intention, sleep restriction, and cognitive-behavior therapy. DISCUSSION: These updated findings provide additional evidence in support of the original review's conclusions as to the efficacy and generalizability of psychological and behavioral therapies for persistent insomnia. Nonetheless, further research is needed to develop therapies that would optimize outcomes and reduce morbidity, as would studies of treatment mechanisms, mediators, and moderators of outcomes. Effectiveness studies are also needed to validate those therapies when implemented in clinical settings (primary care), by non-sleep specialists. There is also a need to disseminate more effectively the available evidence in support of psychological and behavioral interventions to health-care practitioners working on the front line.     

Long-term nightly treatment with indiplon in adults with primary insomnia: results of a double-blind, placebo-controlled, 3-month study

OBJECTIVES: To evaluate the efficacy and safety of indiplon in primary insomnia. DESIGN: Randomized, double-blind, placebo-controlled, 3-month study. SETTING: Multi-center outpatient setting. PATIENTS: N=702 (61% female; mean age 46 years) who met DSM-IV criteria for primary insomnia of at least 3 months' duration. Interventions: Indiplon 10 mg (n=236), indiplon 20 mg (n=233), or placebo (n=233). MEASUREMENTS: Subjective assessment of each of the following: latency to sleep onset (sLSO), total sleep time (sTST), number of awakenings after sleep onset (sNAASO), wake time after sleep onset (sWASO), sleep quality, Insomnia Severity Index (ISI), and global improvement. RESULTS: Treatment with indiplon resulted in significant improvement relative to placebo at all time points for the primary endpoint, sLSO. Mean sLSO at Month 1 for each treatment group was: 10 mg (34.0 +/- 1.3 mins), 20 mg (33.0 +/- 1.3 mins), and placebo (48.7 +/- 1.9 mins; P <0.0001 for both comparisons); efficacy was sustained through Month 3. Both doses of indiplon resulted in significant improvement in sleep maintenance and duration endpoints, sTST and sWASO, as well as sleep quality, ISI, and global improvement at all assessment time points. CONCLUSIONS: In patients with chronic insomnia, long-term nightly treatment with 10 mg and 20 mg doses of indiplon resulted in significant and sustained efficacy in sleep onset, maintenance, and duration, and significant associated improvement in both daytime functioning and quality of life.     

Hypnotic taper with or without self-help treatment of insomnia: a randomized clinical trial

This study aimed to assess the efficacy of a minimal intervention focusing on hypnotic discontinuation and cognitive-behavioral treatment (CBT) for insomnia. Fifty-three adult chronic users of hypnotics were randomly assigned to an 8-week hypnotic taper program, used alone or combined with a self-help CBT. Weekly hypnotic use decreased in both conditions, from a nearly nightly use at baseline to less than once a week at posttreatment. Nightly dosage (in lorazepam equivalent) decreased from 1.67 mg to 0.12 mg. Participants who received CBT improved their sleep efficiency by 8%, whereas those who did not remained stable. Total wake time decreased by 52 min among CBT participants and increased by 13 min among those receiving the taper schedule alone. Total sleep time remained stable throughout withdrawal in both CBT and taper conditions. The present findings suggest that a systematic withdrawal schedule might be sufficient in helping chronic users stop their hypnotic medication. The addition of a self-help treatment focusing on insomnia, a readily available and cost-effective alternative to individual psychotherapy, produced greater sleep improvement.