Отследить переход компьютера в спящий режим

using System.Runtime.InteropServices;
 
    #region prevent screensaver, display dimming and automatically sleeping
    POWER_REQUEST_CONTEXT _PowerRequestContext;
    IntPtr _PowerRequest; //HANDLE
 
    // Availability Request Functions
    [DllImport("kernel32.dll")]
    static extern IntPtr PowerCreateRequest(ref POWER_REQUEST_CONTEXT Context);
 
    [DllImport("kernel32.dll")]
    static extern bool PowerSetRequest(IntPtr PowerRequestHandle, PowerRequestType RequestType);
 
    [DllImport("kernel32.dll")]
    static extern bool PowerClearRequest(IntPtr PowerRequestHandle, PowerRequestType RequestType);
 
    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
    internal static extern int CloseHandle(IntPtr hObject);
 
    // Availablity Request Enumerations and Constants
    enum PowerRequestType
    {
        PowerRequestDisplayRequired = 0,
        PowerRequestSystemRequired,
        PowerRequestAwayModeRequired,
        PowerRequestMaximum
    }
 
    const int POWER_REQUEST_CONTEXT_VERSION = 0;
    const int POWER_REQUEST_CONTEXT_SIMPLE_STRING = 0x1;
    const int POWER_REQUEST_CONTEXT_DETAILED_STRING = 0x2;
 
    // Availablity Request Structures
    // Note:  Windows defines the POWER_REQUEST_CONTEXT structure with an
    // internal union of SimpleReasonString and Detailed information.
    // To avoid runtime interop issues, this version of 
    // POWER_REQUEST_CONTEXT only supports SimpleReasonString.  
    // To use the detailed information,
    // define the PowerCreateRequest function with the first 
    // parameter of type POWER_REQUEST_CONTEXT_DETAILED.
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    public struct POWER_REQUEST_CONTEXT
    {
        public UInt32 Version;
        public UInt32 Flags;
        [MarshalAs(UnmanagedType.LPWStr)]
        public string
            SimpleReasonString;
    }
 
    [StructLayout(LayoutKind.Sequential)]
    public struct PowerRequestContextDetailedInformation
    {
        public IntPtr LocalizedReasonModule;
        public UInt32 LocalizedReasonId;
        public UInt32 ReasonStringCount;
        [MarshalAs(UnmanagedType.LPWStr)]
        public string[] ReasonStrings;
    }
 
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    public struct POWER_REQUEST_CONTEXT_DETAILED
    {
        public UInt32 Version;
        public UInt32 Flags;
        public PowerRequestContextDetailedInformation DetailedInformation;
    }
    #endregion
 
 
 
    /// <summary>
    /// Prevent screensaver, display dimming and power saving. This function wraps PInvokes on Win32 API. 
    /// </summary>
    /// <param name="enableConstantDisplayAndPower">True to get a constant display and power - False to clear the settings</param>
    private void EnableConstantDisplayAndPower(bool enableConstantDisplayAndPower)
    {
        if (enableConstantDisplayAndPower)
        {
            // Set up the diagnostic string
            _PowerRequestContext.Version = POWER_REQUEST_CONTEXT_VERSION;
            _PowerRequestContext.Flags = POWER_REQUEST_CONTEXT_SIMPLE_STRING;
            _PowerRequestContext.SimpleReasonString = "Continuous measurement"; // your reason for changing the power settings;
 
            // Create the request, get a handle
            _PowerRequest = PowerCreateRequest(ref _PowerRequestContext);
 
            // Set the request
            PowerSetRequest(_PowerRequest, PowerRequestType.PowerRequestSystemRequired);
            PowerSetRequest(_PowerRequest, PowerRequestType.PowerRequestDisplayRequired);
        }
        else
        {
            // Clear the request
            PowerClearRequest(_PowerRequest, PowerRequestType.PowerRequestSystemRequired);
            PowerClearRequest(_PowerRequest, PowerRequestType.PowerRequestDisplayRequired);
 
            CloseHandle(_PowerRequest);
        }
    }