6 week old baby only likes to sleep on his side??

Danielle

So since my son was born he was always put to bed in his moses basket on his back to sleep but for the last 2 weeks he just won't settle but has recently discovered rolling onto his side and has been sleeping much more comfortably. He has not however mastered being able to roll onto his tummy.

If this is the only way he'll allow himself to sleep should I let him or should I keep moving him back onto his back?

See pic for context: