Why am I so late to bed?

When I was training loads I'd be physically tired a lot of the time which meant bed before 11 and fast asleep soon after lights out

Now I'm still awake gone midnight and find it really hard to just go to bed

I've literally just had an epiphany about this   

****I'm not really training***

If I actually get knackered each day through physical exertion maybe I'll get to bed earlier?

Let's see if this works

Will go for a run tomorrow and then see if I get to bed any earlier than 00:45