不少人在谈及睡眠时都十分重视睡眠时间。而美国的一项新研究显示，如果只是睡眠时间充足，但睡眠时常中断，有可能会损害长期记忆。
美国斯坦福大学的一个研究小组在新一期美国《国家科学院学报》上报告说，研究者运用光遗传学技术，改变小鼠的特定脑细胞，使这些细胞的“作息”状态受光线控制。当小鼠入睡后，研究人员向它们的大脑发射光脉冲，打断小鼠的睡眠但不影响其总体睡眠时间。
在如此持续干扰一段时间后，研究人员将小鼠一个个单独放入实验箱，每个箱内放有两件物品，其中一件是小鼠早已熟识的旧物，另一件是小鼠此前没见过的东西。一般情况下，如果小鼠能连贯睡眠，那么它观察新物件的时间比旧物长。但实验结果显示，那些不连贯睡眠的小鼠对新旧物品的观察时间和兴趣相同，这说明小鼠的长期记忆受到影响。研究者由此认为，无论睡眠总时长或深度如何，一段最低限度的连贯睡眠对强化记忆至关重要。
英国睡眠协会前会长、睡眠问题专家尼尔·斯坦利在评价上述研究时说，白天人脑累积各种记忆，此后大脑会对白天发生的事情进行分类，有一些需要‘锁’为长期记忆，这一过程发生在深度睡眠时。因此，任何影响睡眠的情况都会或多或少影响这一过程。
斯坦利指出，有一些明显证据表明，睡眠呼吸暂停症患者在“锁”住记忆方面存在一定问题。这种病的症状是睡眠时患者喉咙反复变窄或关闭，限制氧气吸入，致使患者时常从梦中醒来。
此外，斯坦福大学的研究者还认为，睡眠连贯性是影响多种与记忆相关病理状态的主要因素之一，如阿尔兹海默氏症和与年龄有关的其他认知障碍。
生物探索推荐英文摘要：
Optogenetic disruption of sleep continuity impairs memory consolidation
Abstract
Memory consolidation has been proposed as a function of sleep. However, sleep is a complex phenomenon characterized by several features including duration, intensity, and continuity. Sleep continuity is disrupted in different neurological and psychiatric conditions, many of which are accompanied by memory deficits. This finding has raised the question of whether the continuity of sleep is important for memory consolidation. However, current techniques used in sleep research cannot manipulate a single sleep feature while maintaining the others constant. Here, we introduce the use of optogenetics to investigate the role of sleep continuity in memory consolidation. We optogenetically targeted hypocretin/orexin neurons, which play a key role in arousal processes. We used optogenetics to activate these neurons at different intervals in behaving mice and were able to fragment sleep without affecting its overall amount or intensity. Fragmenting sleep after the learning phase of the novel object recognition (NOR) task significantly decreased the performance of mice on the subsequent day, but memory was unaffected if the average duration of sleep episodes was maintained at 62–73% of normal. These findings demonstrate the use of optogenetic activation of arousal-related nuclei as a way to systematically manipulate a specific feature of sleep. We conclude that regardless of the total amount of sleep or sleep intensity, a minimal unit of uninterrupted sleep is crucial for memory consolidation.
