I have to go to work tonight. I'll be sleepy tomorrow morning.
以下のように表現できます。
I have to go to work tonight.(今夜仕事に行かなきゃ)
I'll be sleepy tomorrow morning.(明日の朝眠いだろうな)
I have to work tonight but I have to get up early tomorrow. I will probably be sleepy all morning.(今夜仕事しないといけないけど、明日の朝は早く起きなきゃいけない。おそらく午前中はずっと眠いだろうな)