Al-Bukhari and Muslim report on the authority of al-Bara’ b. ‘Azib that the Prophet (peace be upon him) advised a person that prior to retiring to bed one should perform ablutions and sleep on the right side and offer supplications to Allah.”

We also read in another hadith the Prophet (peace be upon him) admonishing someone who slept on his tummy.

So, we are advised to sleep on the right side and avoid all other positions. Since the Prophet (peace be upon him) is inspired by Allah, we can rest assured that it would be more conducive to our health.

Allah Almighty knows best.