N1 Reading · Test 23

Option 1 is correct. The passage states that sleep is '適応のための技術' (a technique for adaptation) and a '柔軟な生存戦略' (flexible survival strategy) that adjusts to 'さまざまな身体内部および外部の環境条件' (various internal and external environmental conditions). This directly matches option 1's statement that sleep is something which can be adjusted to various conditions in order to survive ('生き抜くために、さまざまな条件に合わせて調整できるものである'). The key idea is flexibility and adaptability.

• 2This option says sleep should have a fixed time allotted for brain rest ('一定の時間確保されるべき'). This contradicts the passage, which emphasizes sleep's flexibility ('柔軟な生存戦略') and diversity ('多様性に富むもの'). The passage argues against fixed time requirements.
• 3This option says sleep threatens life and should be avoided as much as possible ('できるだけ避けるべき'). While the passage does mention sleep is a '命懸け' (life-risking) act, it presents this as a reason why sleep conditions must be carefully arranged—not as a reason to avoid sleep. Sleep is described as essential for survival, not something to avoid.
• 4This option says sleep is prioritized over other activities for environmental adaptation ('他の活動より優先される'). This is the opposite of what the passage states: '優先してなすべきことがほかにあるから、睡眠は、すなおに順位をそちらに譲るのが通例だ' (when there are other things that should take priority, sleep ordinarily yields its turn).

• 適応てきおう — adaptation, adjusting to conditions
• 生存戦略せいぞんせんりゃく — survival strategy
• 柔軟じゅうなん — flexible, adaptable
• 多様性たようせい — diversity, variety

Option 2 is correct. The underlined phrase '睡眠を人為的な規則で拘束した' (constrained sleep with artificial rules) is explained by the following sentences: '社会活動や季節変化などをもとにして、睡眠の持つ多様性を一定の枠の中に押し込めてしまった' (based on social activities and seasonal changes, the diversity of sleep was forced into a fixed framework) and '大人は一日に八時間まとめて寝るのが基準であるかのように考える傾向が定着した' (the tendency to think adults should sleep eight hours straight became established). Option 2 captures this: allocating a certain fixed time within the day for sleep ('一日のうちの、一定の時間を睡眠に当てることにした').

• 1This option says sleep time was made as short as possible ('できるだけ短くする'). The passage does not say humans tried to minimize sleep time; it says they standardized it into a fixed framework (e.g., eight hours). Shortening sleep is not the point.
• 3This option says sleep time was reduced to match activity time ('活動時間に合わせて、睡眠時間を減らす'). While the passage mentions social activities as a basis for the framework, it does not say sleep was reduced—rather, it was standardized/constrained into a set pattern.
• 4This option says each person decided sleep time based on their own conditions ('各自の条件に合わせて、睡眠時間を決める'). This is the opposite of what the passage says: humans constrained sleep's natural diversity into a uniform rule, rather than allowing individualized adjustment.

• 人為的じんいてき — artificial, man-made (as opposed to natural)
• 拘束こうそく — constraint, restriction, binding
• 枠わく — framework, bounds, limits
• 押し込める（おしこめる） — to force into, to confine within

Option 1 is correct. The passage's overall argument is: sleep is naturally a flexible, diverse survival strategy that adapts to conditions, but humans have artificially constrained it into uniform rules (like the eight-hour standard), which has no biological basis and causes unnecessary anxiety about 'sleep debt.' The author's main point is that human sleep time should not be uniformly fixed—'人間の睡眠時間は一様に決めるようなものではない.' This is supported by the opening question ('八時間...特別な根拠があるのか'), the emphasis on sleep's natural diversity ('睡眠は本来多様性に富むものだ'), and the conclusion that 'この数値に生物学的な根拠はない' (this number has no biological basis).

• 2This option says human sleep methods cannot be compared with other creatures ('他の生き物と比べられるものではない'). The passage actually states the opposite: '人間の睡眠も、生物学的にはまったく同様の適応力を備えている' (human sleep also has exactly the same adaptive capacity biologically), implying humans and other animals share similar sleep mechanisms.
• 3This option says humans, like other creatures, use sleep as a survival strategy ('人間も他の生き物と同様に、睡眠をとることが生存戦略となっている'). While this is mentioned in the passage, it is a supporting point, not the author's main argument. The main thrust is that humans have unnaturally constrained this flexible strategy with artificial rules.
• 4This option says humans needed different sleep times from other creatures due to social activities ('他の生き物と異なる睡眠時間が必要になった'). The passage does not argue that humans biologically need different sleep times; rather, it argues that the artificial standardization of sleep lacks biological basis and that humans still possess the same adaptive capacity as other animals.

• 一様いちように — uniformly, equally, in the same way
• 根拠こんきょ — basis, grounds, evidence
• 負債ふさい — debt (here used metaphorically as 'sleep debt')
• 定着ていちゃく — becoming established, taking root