I only got three hours of sleep because I needed to get on the first train of the day.
I only slept three hours so I could catch the first train.
こんにちは。
・I only got three hours of sleep because I needed to get on the first train of the day.
「始発に乗らなきゃいけなかったから三時間しか寝れなかった」
・I only slept three hours so I could catch the first train.
「始発に乗るために三時間しか寝なかった」
上記のような言い方ができます。
only で「しか」を強調できます。
「始発」は first train (of the day) と表現できます。
ぜひ参考にしてください。
I only slept three hours because I needed to catch an early train
Because I needed to catch the first train,I only had three hours sleep
First example uses subordinating conjunction because to join clauses. Telling why you only slept three hours. Same in second example. Because has moved to front of sentence putting adverbial clause at the start
My sleep was limited to 3 hours due to an early rail departure
I only managed to get 3 hours sleep last night because I caught the first train.
The first sentence adequately describes what has happened. Whether the train was the first, or just an early train, is probably not very significant although of course, you could mention it was the first train if you like. Sentence two is a little more casual than the first and would be appropriate if you are talking about feeling a little tired or sleepy.
Since I need to be on the first train I only get 3 hours of sleep.
In order to catch the first train I need to wake up early, so I only get 3 hours of sleep.
These two sentences will help you express the idea that you only get 3 hours of sleep because you need to catch the first train. In the second sentence you will see the word catch. Although the word catch has different meanings in this sentence it means to be at a certain location in order to experience something. So, for example, if you want to see a movie at 11:00 you can say 'I'm going to catch the 11:00 showing'.
これら2つの例文は、始発に乗らなくてはならないため睡眠に取れる時間が3時間しかないという考えを表現するのに役立ちます。
2番目の例文には、catchという単語が入ってますが、この文中のcatchという単語には違う意味があります。何かを体験（経験）するためにある特定の場所にいるという意味です。
例えば、11時に映画を観たいなら、I'm going to catch the 11:00 showing（11時から始まる映画を観に行きます）と言えるでしょう。
I only got 3 hours of sleep, I needed to get on the first train.
To explain that you got very little sleep because you needed to catch the first train, you can say:
"I only got 3 hours of sleep, I needed to get on the first train."
「始発に乗らないといけなかったのでほとんど寝られなかった」は次のように言えます。
"I only got 3 hours of sleep, I needed to get on the first train."（3時間しか寝られませんでした。始発に乗らないといけなかったので）
イギリス 
アメリカ合衆国 
日本 
南アフリカ 
