Cizza Giovanni, Piaggi Paolo, Rother Kristina I, Csako Gyorgy
Section on Endocrinology & Genetics, Program on Developmental Endocrinology & Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States of America.
Obesity Research Center, Endocrinology Unit, University Hospital of Pisa, Pisa, Italy.
PLoS One. 2014 Aug 20;9(8):e104176. doi: 10.1371/journal.pone.0104176. eCollection 2014.
To evaluate the effects of study participation per se at the beginning of a sleep extension trial between screening, randomization, and the run-in visit.
Subjects were screened, returned for randomization (Comparison vs. Intervention) after 81 days (median), and attended run-in visit 121 days later.
Outpatient.
Obese (N = 125; M/F, 30/95; Blacks/Whites/Other, N = 73/44/8), mean weight 107.6±19.7 kg, <6.5 h sleep/night.
Non-pharmacological sleep extension.
Sleep duration (diaries and actigraphy watch), sleep quality (Pittsburgh Sleep Quality Index), daily sleepiness (Epworth Sleepiness Scale), fasting glucose, insulin and lipids.
Prior to any intervention, marked improvements occurred between screening and randomization. Sleep duration increased (diaries: 357.4 ±51.2 vs. 388.1±48.6 min/night; mean±SD; P<0.001 screening vs. randomization; actigraphy: 344.3 ±41.9 vs. 358.6±48.2 min/night; P<0.001) sleep quality improved (9.1±3.2 vs. 8.2±3.0 PSQI score; P<0.001), sleepiness tended to improve (8.9±4.6 vs. 8.3±4.5 ESS score; P = 0.06), insulin resistance decreased (0.327±0.038 vs. 0.351±0.045; Quicki index; P<0.001), and lipids improved, except for HDL-C. Abnormal fasting glucose (25% vs. 11%; P = 0.007), and metabolic syndrome (42% vs. 29%; P = 0.007) both decreased. In absence of intervention, the earlier metabolic improvements disappeared at the run-in visit.
Relatively small sample size.
Improvements in biochemical and behavioral parameters between screening and randomization changed the "true" study baseline, thereby potentially affecting outcome. While regression to the mean and placebo effect were considered, these findings are most consistent with the "Hawthorne effect", according to which behavior measured in the setting of an experimental study changes in response to the attention received from study investigators. This is the first time that biochemical changes were documented with respect to the Hawthorne effect. The findings have implications for the design and conduct of clinical research.
ClinicalTrials.gov NCT00261898.
评估在一项睡眠延长试验开始时，从筛查、随机分组到导入期访视期间参与研究本身的影响。
对受试者进行筛查，81天（中位数）后返回进行随机分组（比较组与干预组），121天后参加导入期访视。
门诊。
肥胖者（N = 125；男/女，30/95；黑人/白人/其他，N = 73/44/8），平均体重107.6±19.7千克，每晚睡眠<6.5小时。
非药物性睡眠延长。
睡眠时间（日记和活动记录仪）、睡眠质量（匹兹堡睡眠质量指数）、每日嗜睡程度（爱泼华嗜睡量表）、空腹血糖、胰岛素和血脂。
在任何干预之前，筛查和随机分组之间出现了显著改善。睡眠时间增加（日记记录：357.4±51.2对388.1±48.6分钟/晚；均值±标准差；筛查与随机分组相比，P<0.001；活动记录仪记录：344.3±41.9对358.6±48.2分钟/晚；P<0.001），睡眠质量改善（匹兹堡睡眠质量指数评分：9.1±3.2对8.2±3.0；P<0.001），嗜睡程度有改善趋势（爱泼华嗜睡量表评分：8.9±4.6对8.3±4.5；P = 0.06），胰岛素抵抗降低（0.327±0.038对0.351±0.045；快速胰岛素敏感指数；P<0.001），血脂改善，但高密度脂蛋白胆固醇除外。空腹血糖异常（从25%降至11%；P = 0.007）和代谢综合征（从42%降至29%；P = 0.007）均有所下降。在没有干预的情况下，早期的代谢改善在导入期访视时消失。
样本量相对较小。
筛查和随机分组之间生化和行为参数的改善改变了“真正的”研究基线，从而可能影响结果。虽然考虑了均值回归和安慰剂效应，但这些发现最符合“霍桑效应”，即根据该效应，在实验研究环境中测量的行为会因研究调查人员给予的关注而发生变化。这是首次记录到与霍桑效应相关的生化变化。这些发现对临床研究的设计和实施具有启示意义。
ClinicalTrials.gov NCT00261898
