I notice something interesting. 

My mood and energy level vary from morning to night. In the morning when I wake up, my body brims with energy, eagerness, and hope. I’m full of plans and cannot wait to execute them. That is indeed the best time in the day for me. But then, when the day dies and darkness descends, when activities cease and birds stop singing to hide into their nests, my hope seems to die along. I feel tired, and sad for no particular reason. And most of all, lonely.

Was Philip Larkin feeling the same way when he woke up in the dark of the night? 

I work all day, and get half-drunk at night. 
Waking at four to soundless dark, I stare. 
In time the curtain-edges will grow light. 
Till then I see what’s really always there: 
Unresting death, a whole day nearer now, 
Making all thought impossible but how 
And where and when I shall myself die.