The HUD functions are organised as follows:

Your character now is a human! If you’ve ever played The Sims you’ll know what this is like. Your character has six regular needs, health, and a hidden “fitness” stat, and clicking a need tells you how filled it is, or how long it will take to deplete, depending on the need:

• Toilet: This need goes down whenever you eat or drink something, with a delay. To fill it up again, you need to use one of the toilets on sim. Currently, all Common Rooms as well as the Staff Living Quarters have bathrooms with working toilets.
• Hunger: It takes 12 online hours to deplete hunger. Food can be found in the Great Hall during meal times (found on the calendar), and a few snacks can be had from tables in the Common Rooms. You can also buy snacks and candy in Hogsmeade (more on buying/selling in the Inventory section).
• Thirst: It takes 10 online hours to deplete thirst, and drinks can be likewise found in the Great Hall during meal times. You can get drinks in Hogsmeade or the hospital wing, and water is free so stock up!
• Social: Social is the only need that depletes even when you’re offline. It takes 24 real-world hours to deplete, and in order to raise it you need to RP! Only emotes raise it, however, so you must use some titler/chatter or /me to raise it.
• Energy: Energy takes 12 online hours to deplete, and can be refilled on beds in the Dormitories and Living Quarters. You can also take naps by clicking the appropriate option on the Main Menu (but posting or moving wakes you up!). Being tired will affect your ability to cast spells, transfigurations, and dodge successfully, so make sure you’re rested up!
• Hygiene: It takes 10 online hours to deplete hygiene, and it can be refilled with sinks and showers available in the bathrooms around the sim.
• Health: Health only goes down when your other needs get to 0, when you overeat, or when certain things happen (such as being poisoned or being too close to the Whomping Willow). Health may be raised back up by paying a visit to the Hospital Wing and spending a while in bed. Note that Health will only go up while you’re ICly on the bed, so you need to stay there a while. You may also heal yourself or another player with the use of healing spells, which work much faster than laying in a hospital bed. There is a bell in the Hospital Wing you may use to page players who play healer characters. When you click the “Health” button, both your character’s Fitness and illnesses, maladies, or injuries they might’ve gotten are shown.
• Fitness: There is also a hidden stat called “Fitness.” It goes down whenever you eat or drink anything (except for water) or lose Health, and goes up when you walk, run, or fly on a broomstick. You may also dodge and then post RP to gain fitness. Performing physical activities will make you more tired, hungry, thirsty, and in need of a shower. Be sure not to overdo it! There is a limit to how much fitness you can gain per day, and over-exercising will eventually deplete your health. Everyone starts out at 50% fitness.

Your needs are supposed to be an aid to RP, and your character will never die, nor will the HUD post anything in local due to low needs. When your needs start getting low, they will blink red.

IMPORTANT: There are two things needs do affect, though: skill use and Quidditch. Your health and energy are modifiers to skill rolls relative to how full they are. For example if your energy is 50% full, you will have a 5% less chance at being able to successfully cast any particular spell. 75% health is equivalent to a strong flu, 50% health is pneumonia, 25% you’re bedridden, and 0% you’re basically catatonic. RP your Health! And RP your visits to the Hospital Wing. Additionally, Health also caps other stats (except for Hunger and Thirst), so if you’re at (say) 50% Health your other stats can only get as high as 75%; if you’re at 0% Health the maximum everything else can reach is 50%.