I hear ambien works well also.
I couldn't get my Mini to sleep using my P2140. Helped by OCS (of the QCar team) and Mike at Carnetix I finally got this extremely simple fix. Now it sleeps and unsleeps beautifully.
1) Update the firmware of your device to the latest (at the time of writing 1.8.3). Mine was 1.0 when I bought it only a couple of months ago. You currently need to use a Windows machine to do this but hopefully this may change in time.
2) In the Settings screen of the PSUMoni application change the unit from Hibernate to Standby
That was all that was required.
I used OCS' port of the PSUMoni application running natively on my Mac. Lovely! Hope this may help some others.
[HL]Warning - NSFW [/HL]