Waking up several times throughout the night is a natural occurrence often due to sleep architecture. Sleep architecture refers to the stages of sleep people cycle through during the night in about 90 to 120-minute intervals (间隔). The cycle begins with a light sleep that transitions into a deeper sleep, and then into the deepest sleep that occurs in the third stage, often referred to as “slow-wave sleep,” Dr. Brandon Peters-Mathews said. During the fourth stage, known as rapid eye movement (REM) sleep, brain activity picks up to levels that almost reach normal activity while awake — it’s after this stage when people often wake up naturally, he said, and once they fall back asleep the cycle begins again.

“Because we tend to go to bed at roughly the same time on a nightly basis, and these cycles are roughly the same length, we may wake at the same time in the night,” Peters-Mathews said. Most of these awakenings will be brief and forgettable, but “there might be one or two cycles into the night that we wake up and look at the clock and are aware of the time.”

Waking up several times throughout the night is typically not disruptive to one’s health, as long as falling back asleep occurs within about five to 10 minutes, said Dr. Michelle Drerup. But on the other hand, when people find themselves waking up multiple times within the hour, that could cause a sleep cycle to be fragmented and the individual might not get any deep sleep, Drerup said. These frequent awakenings could be a sign of sleep disorders such as sleep apnea or nocturia, she added.

It’s often a person’s emotional response to the awakening that can pose challenges, Peters-Mathews said, and could result in someone developing secondary insomnia (失眠) if their reaction causes long periods of wakefulness. “If somebody wakes in the night, and the first thing they do is look to their alarm clock, and see what time it is, and that’s something that makes them feel frustrated or upset or anxious as they anticipate the next day — it’s the reaction that’ problematic,” he said. 

1.What can we know from the first paragraph?

A The sleep cycle makes people awake.

B There are four stages in a sleep cycle.

C A slow-wave sleep lasts for about 2 hours.

D People often wake up from REM sleep.

解析：选B。B 细节理解题。根据第一段的“The cycle begins with a light sleep that transitions into a deeper sleep, and then into the deepest sleep...During the fourth stage, known as rapid eye movement (REM) sleep”可知，睡眠周期从浅睡眠开始，过渡到较深度睡眠，然后进入第三阶段的深度睡眠，第四阶段被称为快速眼动（REM）睡眠。即一个睡眠周期有四个阶段。故选B。

2.What does the underlined word “disruptive” mean?

A Special.

B Immediate.

C Harmful.

D Beneficial.

解析：选C。C 词义猜测题。根据划线词后面的内容“as long as falling back asleep occurs within about five to 10 minutes”只要在5到10分钟内重新入睡；并结合后文的“But on the other hand, when people find themselves waking up multiple times within the hour”“These frequent awakenings could be a sign of sleep disorders”谈到在一个小时内频繁醒来则可能意味着有睡眠问题。由此推断，整晚醒来好几次一般不会对健康“有害”。故选C。

3.What can be inferred from the last paragraph?

A Some people are emotional at night.

B Looking for clock makes people stressed.

C People’s emotional reaction affects sleep quality.

D Waking up in the middle of the night is not rare.

解析：选C。C 推理判断题。根据最后一段中的“It’s often a person’s emotional response to the awakening that can pose challenges...could result in someone developing secondary insomnia (失眠) if their reaction causes long periods of wakefulness”一个人对醒来的情绪反应会带来挑战，如果他们的反应导致长时间的清醒，这可能会导致继发性失眠；以及“it’s the reaction that’ problematic”有问题的是他们的反应。由此可知，人的情绪反应会影响睡眠质量。故选C。

4.Why does the author write the text?

A To stress the importance of sleep.

B To introduce sleep architecture.

C To describe how to sleep well at night.

D To explain why people might be waking up.

解析：选D。D 推理判断题。通读全文内容可知，本文主要描述了有的人为何会一晚上醒来几次，由此可知，本文的目的是对此进行解释。故选D。