《key to happiness》的詞曲作者和演唱者不詳，只有歌詞可供參考。歌詞如下：
Key to happiness
In the palm of your hand
You got the key to happiness
You just need to understand
Believe in what you dream
Believe in what you can
Your key to happiness
Is within reach, oh yeah
Key to happiness, yeah
Hold on, you won't lose it now
With every storm, there's a rainbow
If you believe, then you'll be fine
What you feel, is the real thing tonight
Your key to happiness
Is within reach, oh yeah
Key to happiness, yeah
Now that you found it, never let it go
Let it guide you, in every way, oh yeah
And in every storm, there's a rainbow人體生物鐘 凌晨兩點整，我醒了，感覺身體很疲憊，這是怎么回事？
凌晨兩點整醒來並感到身體疲憊可能是由於多種原因導致的。首先，睡眠質量不好可能是導致這種情況的原因之一。睡眠質量不好可能是由於睡眠環境不佳、睡眠時間不足或睡眠姿勢不適等原因引起的。此外，身體疲勞也可能是由於缺乏運動或飲食不健康等原因導致的。此外，精神壓力和焦慮情緒也可能影響睡眠質量，導致凌晨兩點醒來並感到疲憊。如果這種情況持續存在，建議尋求醫生的幫助以了解更多原因並尋求相應的解決方案。在改善睡眠質量、增加運動和調整飲食等方面進行改善，可能會對緩解這種情況有所幫助。