Getting baby to take both breasts

[shouldistop]

At the 4am feed quite often my 1mo will only take one breast, sleep for 60-90mins then start getting fussy and wants fed again.
How do I encourage him to take both breasts and fill himself up?
I've tried the usual things, rubbing his hands etc.
Is there a trick I'm missing?
I can't sleep in in the morning as I have a 4yo so I'm basically starting the day at 4am sometimes

Your baby isn't waking because he's only had one breast - babies feed more often at night to boost supply (prolactin levels are higher). Both of mine usually only had one breast at a time. He will start to go longer between feeds soon.

The times he has both breasts he sleeps on til 6.40/7am