Sudden Sleep.SUDDENLY SLEEPING HELP..

Question

Paris France. Feb 2006.
SUDDENLY SLEEPING. Like, I'd be typing along, with the powercord plugged in and a full battery charge, and the display goes blank and the whole machine sounds like it's going into hibernation. I can always get it back just by pressing a key and waiting a few seconds, but it's very strange and disturbing, and besides, it's totally aggravating! Have anyone found a solution to this bloody problem. please HELP... I am now on 10.4.5
Help..sudden sleep.
Victor

Answer 1

Mac OS X: Why your Mac might not sleep or stay in sleep mode
Learn why your Mac might not go to sleep when you expect it to, or why it might not stay in sleep mode. What's sleep mode? It's a low power, energy-saving feature of that offers both environmental and economic benefits, as well as helping to extend the life of batteries and displays.
On the other hand, you probably don't want the computer to sleep at certain times even if you're not using the keyboard or mouse, such as when you are:
While watching a DVD movie
Listening to your iTunes music library
Running an automated backup
Away from your computer while downloading large files
Tip: For troubleshooting tips, go to the "How can I determine what is causing a sleep issue and resolve it?" section at the bottom of this article.
Why doesn't the computer go to sleep at the expected time based on Energy Saver settings?
You can configure Energy Saver preferences to set your computer to automatically sleep after a specified period of time; an internal counter called a "sleep timer" monitors the amount of time your computer has been inactive. When the counter's time matches the amount of time you specified, the computer enters sleep mode and displays a pulsing power light.
Some things reset the sleep timers, preventing the computer from sleeping:
Hard drive access (even if you're not using the computer, a running application might be accessing your drive, such as when downloading a large file or listening to music in iTunes)
Moving the mouse or using a portable Mac's trackpad, pressing a mouse button, or pressing a key on the keyboard
Some System Preferences settings (see below)
Open applications (see below)
Input devices (see below)
Expansion cards (see below)
Additional drives, such as USB, FireWire, DVD, or CD drives (see below)
Some System Preferences settings affect sleep
Energy Saver
Energy Saver is a System Preference that can help you optimize energy settings as well as sleep times and processor usage. Note that processor controls are not used for Intel-based Macs because they have a built-in power-saving feature. Only PowerPC-based Macs display processor controls.
Bluetooth
You can allow Bluetooth devices to wake a sleeping computer by enabling "Allow Bluetooth devices to wake this computer" in Bluetooth preferences. Simply having a bluetooth device paired does not prevent a system from sleeping.
Spotlight
Your computer will not sleep if Spotlight is indexing content, because that requires hard disk access. For example, if you just installed or reinstalled Mac OS X, Spotlight may need a while to index content.
Sharing
Network activity can reset the sleep timer, too. For example, leaving a self-refreshing Web page open in a Web browser.
In these situations, the display will sleep (unless Energy Saver preferences is configured to never let the display sleep) but the processor will continue to be awake and the power light will remain on.
Keyboard, mouse, other input devices can affect sleep
Keyboard presses and mouse button clicks can wake a sleeping computer. Mouse movement alone will only wake a sleeping display. Even though your Mac may be in sleep mode, it remains aware of keyboard presses and mouse clicks. If you move a mouse, press a key, or use a different input device, the sleep timer counter will reset.
Open applications can affect sleep
Software that accesses the hard drive will delay sleep mode until it is either quit or done accessing the drive, for example:
A self-refreshing Web page open in Safari.
Songs playing in iTunes.
A movie disc playing in DVD Player.
However, this can also occur in subtle ways you might not expect:
An application window might display text that periodically changes (such as a clock).
If an application uses a custom font to display text but the font resource is marked purgeable, then at some point the memory manager will purge the font from memory. When the application tries to draw text using that font again, it will be loaded from the hard drive, resetting the sleep timer.
Applications can be designed to keep the system awake and prevent idle sleep indefinitely. In developer lingo, an application may explicitly prevent system sleep by calling IORegisterForSystemPower(), and calling IOCancelPowerChange() when it receives a power management kIOMessageCanSystemSleep notification.
Expansion cards can affect sleep
Some PCI expansion cards can prevent sleep. If a card's Mac OS X device driver is not properly power managed, the computer will be unable to safely remove power from it, preventing the system from entering full sleep. Instead, the system enters a state named "Doze".
Some kinds of PCI cards prevent any kind of sleep mode--your system will not go into low-power mode during long periods of inactivity. The computer fans may run excessively when this is the case.
Other hard drives (USB, FireWire, ATA), optical media drives (DVD, CD) can affect sleep
If there is disk accesses activity at least once a minute on disks such as ATA drives, FireWire drives, and USB drives, the computer will not idle sleep.
How can I determine what is causing a sleep issue and resolve it?
As mentioned above, these are the most likely causes and solutions for sleep issues:
Sharing preferences: Enabling sharing for any connections can potentially disable sleep. Turn off file sharing if it's not being used.
Bluetooth settings: Bluetooth can wake your computer if you set the "Allow Bluetooth devices to wake this computer" checkbox in Bluetooth System Preferences.
Is a keyboard and mouse connected and working correctly?
Do you have any other external USB or FireWire devices connected? Try removing them one by one or disconnect when not in use.
Is Spotlight indexing? This can take anywhere from several minutes to several hours after a new installation. Indexing prevents idle sleep.
Additional Software: Try a Safe Boot to help isolate a software issue.
Sound check: Put your ear near your computer. Do you hear the sounds of hard disk access (a clicking or "clacking")?
Energy Saver settings: If the computer and display sleep timers are set to Never, the computer will not sleep.
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