prova a disattivare il Safe Sleep:
"Safe Sleep" is a function writes the contents of RAM to a hard disk buffer. The buffer is then accessed and restored to RAM, creating an effect similar to merely putting the system to sleep though it has actually been turned off (no power being used).
Mac OS X uses virtual memory data (RAM contents naturally stored on disk as part of the virtual memory scheme) to formulate the sleepimage file. When the system is put to sleep, Mac OS X culls from physical RAM whatever data it cannot replicate from virtual memory and adds it to the sleepimage file. As such, if the system is put to sleep abruptly or something goes wrong during the write process, sleep can fail to properly occur.
If you think safe sleep might be to blame for your regular sleep issues, you can disable it by opening the Terminal (located in Applications/Utilities) and entering the following command:
sudo pmset -a hibernatemode 0
then pressing return.
You can then select "Go to Folder" under the "Go" menu in the Finder, and enter: /private/var/vm then press return, and drag the file sleepimage to the Trash..
In order to re-enable Safe Sleep, use the command:
sudo pmset -a hibernatemode 3
in the Terminal.
FONTE: http://www.macfixit.com/article.php?sto ... 9234938244