A hypothesis on male libido

This is just an observation from personal experience, men who sleep lying face down exhibit an insatiable long-lasting sexual urge. This is good if it's all released to the girlfriend, bad if it's released outside the relationship. Of course this is just an observation and an unusual hypothesis for psychology and sex therapy majors to test. I'm wondering that if it's true though how would a girl practically convince or make her guy to change his sleeping positions depending on the needs of the relationship over time! :)

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