Idle and deep sleep are functions that are designed to prolong battery life.
When you press any button on your Suunto D5, it goes to active mode and the display backlight is activated (if turned on) and the seconds become visible on the watch face (red rectangle moving). After two minutes, the device goes to idle mode: the number of colors is reduced to save power and moving elements are turned off.
Deep sleep is a function that prolongs battery life when Suunto D5 has not been used for some time. Deep sleep is activated when one day has passed since:
Suunto D5 wakes up when it is connected to a PC/charger, when a button is pressed, or when the water contact gets wet.
When not used, your Suunto D5 goes from active mode to idle mode and finally to deep sleep.
Wake up your Suunto D5 by pressing any button, or connecting to a computer / charger, or activating the water contact by immersing the device in water.
If your Suunto D5 runs out of battery when in deep sleep, you can only wake up your device by connecting to a charger or a computer with a USB cable of 5Vdc.