My Apple Magic Mouse, connected to my Razer Blade (2014), randomly disconnects and won't reconnect. It's irritating, frustrating and makes me reconsider switching back to Mac. I knew it was almost certainly being cause by the sleep settings but I couldn't locate those. I found a support post when searching for "bluetooth mouse temporarily disconnects windows 8.1" that had these instructions:

1. Go to Control Panel
2. Go to More Settings
3. Search for BLUETOOTH and bluetooth options will appear under DEVICES AND PRINTERS
4. select CHANGE BLUETOOTH SETTINGS
5. Select the HARDWARE TAB
6. Select the GENERIC BLUETOOTH ADAPTER
7. Click the PROPERTIES Button
8. Click the CHANGE SETTINGS button
9. Select the POWER MANAGEMENT Tab
10. Uncheck the box that says "Allow the computer to turn off the device to save power"

and OK your way back out. (2)