import ctypes, atexit

# DWORD SetThreadExecutionState(EXECUTION_STATE esFlags);
kernel32 = ctypes.WinDLL("kernel32", use_last_error=True)
SetThreadExecutionState = kernel32.SetThreadExecutionState
SetThreadExecutionState.argtypes = [ctypes.c_uint]
SetThreadExecutionState.restype  = ctypes.c_uint

ES_CONTINUOUS       = 0x80000000
ES_DISPLAY_REQUIRED = 0x00000002
# Optional: ES_SYSTEM_REQUIRED = 0x00000001

def keep_awake():
    r = SetThreadExecutionState(ES_CONTINUOUS | ES_DISPLAY_REQUIRED)
    if r == 0:
        raise ctypes.WinError(ctypes.get_last_error())

def clear_awake():
    SetThreadExecutionState(ES_CONTINUOUS)

atexit.register(clear_awake)
keep_awake()
input("Display is kept on. Press Enter to release and exit...")