Institute of Physiology v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Chronobiol Int. 2011 Aug;28(7):630-7. doi: 10.3109/07420528.2011.596983.
Attention-deficit/hyperactivity disorder (ADHD) is the most common neurobehavioral disorder of childhood. Problems with sleep structure, efficiency, and timing have been reported in some, but not all, studies on ADHD children. As the sleep-wake cycle belongs to circadian rhythms, the timekeeping circadian system might be involved in ADHD. To assess whether the circadian system of ADHD children differs from that of controls, the rhythm of the pineal hormone melatonin was used as a reliable marker of the system. Saliva from 34 ADHD and 43 control 6- to 12-yr-old children was sampled at 2-h intervals throughout the entire 24-h cycle, and the melatonin profiles of the ADHD and control children were compared. The nocturnal melatonin peaks of the ADHD and control group did not differ significantly. The high nocturnal interindividual variability of the peaks seen in adulthood was present already in the studied children. The 24-h melatonin profiles of all the ADHD subjects did not differ significantly from those of the control subjects. Categorization of subjects according to age, into groups of 6- to 7-yr-old (9 ADHD, 5 control), 8- to 9-yr-old (16 ADHD, 26 control), and 10- to 12-yr-old (9 ADHD, 12 control) children, revealed significant differences between the ADHD and control group in the melatonin rhythm waveform, but not in nocturnal melatonin peaks; the peaks were about the same in both groups and did not change significantly with increasing age. In the oldest, but not in the younger, children, the melatonin signal duration in the ADHD group was shorter than in the control group. The difference might be due to the fact that whereas in the control group both the evening melatonin onset and the morning offset phase delayed in the oldest children relative to those in the youngest children, in the ADHD group only the onset, but not the offset, phase delayed with increasing age. The data may indicate subtle differences between the circadian system of ADHD and control children during development.
注意缺陷多动障碍（ADHD）是儿童中最常见的神经行为障碍。一些研究报告了 ADHD 儿童存在睡眠结构、效率和时间方面的问题，但并非所有研究都如此。由于睡眠-觉醒周期属于昼夜节律，因此计时昼夜节律系统可能与 ADHD 有关。为了评估 ADHD 儿童的昼夜节律系统是否与对照组不同，我们使用松果腺激素褪黑素的节律作为系统的可靠标志物。从 34 名 ADHD 儿童和 43 名对照 6 至 12 岁儿童的唾液中每隔 2 小时取样一次，整个 24 小时周期，比较 ADHD 儿童和对照组儿童的褪黑素图谱。ADHD 组和对照组的夜间褪黑素峰值没有显著差异。在研究的儿童中已经存在成年人中夜间个体间峰值高度的高变异性。所有 ADHD 受试者的 24 小时褪黑素图谱与对照组受试者的没有显著差异。根据年龄将受试者分类为 6 至 7 岁（9 名 ADHD，5 名对照）、8 至 9 岁（16 名 ADHD，26 名对照）和 10 至 12 岁（9 名 ADHD，12 名对照），发现在褪黑素节律波形上，ADHD 组和对照组之间存在显著差异，但在夜间褪黑素峰值上没有差异；两组的峰值相同，且随年龄增长没有明显变化。在年龄较大的儿童中，但不在年龄较小的儿童中，ADHD 组的褪黑素信号持续时间比对照组短。这种差异可能是由于在对照组中，与年龄最小的儿童相比，年龄较大的儿童的夜间褪黑素开始时间和早晨褪黑素结束时间均延迟，但在 ADHD 组中，只有开始时间，而不是结束时间，随着年龄的增长而延迟。这些数据可能表明 ADHD 和对照组儿童在发育过程中昼夜节律系统存在细微差异。
