Meaning: In this context, 'sound' means healthy or undisturbed, referring to good quality sleep that children typically experience.

Wrong options:

• right: The word 'right' implies correctness but does not convey the quality of sleep patterns, making it contextually inappropriate here.
• bright: While 'bright' can describe intelligence or vividness, it does not relate to sleep patterns, thus failing to fit the context.
• upright: The term 'upright' refers to a physical position and does not apply to sleep patterns, making it irrelevant in this context.

Correct answer: successfully

Explanation: The word 'successfully' indicates that children are able to achieve the act of sleeping for the required duration, fitting grammatically and contextually as it describes the effectiveness of their sleep.

Meaning: 'Successfully' means achieving a desired outcome, in this case, being able to sleep for the recommended hours.

Wrong options:

• range: The word 'range' suggests variation but does not convey the ability to sleep, making it contextually incorrect.
• exchange: 'Exchange' implies a trade or swap, which does not relate to the act of sleeping, thus failing to fit the context.
• nicely: While 'nicely' suggests a pleasant manner, it does not convey the effectiveness of sleeping for the required hours, making it less suitable.

Correct answer: influence

Explanation: The word 'influence' appropriately describes how external factors can affect teenagers' sleep patterns, fitting grammatically and contextually as it indicates a change caused by external circumstances.

Meaning: 'Influence' means to have an effect on something, in this case, how schedules can affect sleep patterns.

Wrong options:

• upsurge: The term 'upsurge' refers to a sudden increase, which does not apply to the context of affecting sleep patterns, making it incorrect.
• enable: 'Enable' suggests allowing something to happen, but it does not fit the context of how schedules affect sleep, thus being inappropriate here.
• distress: While 'distress' indicates suffering or anxiety, it does not accurately describe the effect of schedules on sleep patterns, making it contextually unsuitable.