在Android中實現定時的gotosleep功能可以通過使用AlarmManager來實現。以下是一個簡單的步驟：

1. 在AndroidManifest.xml中添加權限：

<uses-permission android:name="android.permission.WAKE_LOCK" />

2. 創建一個BroadcastReceiver類，用于接收AlarmManager的廣播：

public class SleepReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
        PowerManager.WakeLock wakeLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "YourApp:WakeLock");
        wakeLock.acquire();
        wakeLock.release();
    }
}

3. 在MainActivity中設置AlarmManager：

public class MainActivity extends AppCompatActivity {
    private PendingIntent pendingIntent;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
        Intent intent = new Intent(this, SleepReceiver.class);
        pendingIntent = PendingIntent.getBroadcast(this, 0, intent, 0);

        // 設置定時任務，此處為5秒后執行
        alarmManager.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + 5000, pendingIntent);
    }
}

這樣就可以在Android中實現定時的gotosleep功能了。當AlarmManager觸發時，會發送廣播給SleepReceiver，并在其中調用PowerManager來使設備進入睡眠狀態。