As even the casual viewer of "Bridezilla" knows, big events have a way of bringing out the worst in people.
Especially when those people are children who haven't yet developed a sense of proportion about, well, pretty much anything.
Their birthday party looms large in their little world.
It is a source of power ("I'm uninviting you to my birthday party"), the day when they rule the world, the day that all the attention and focus is on them.
Seductive, n'est pas? So, when the party is over and the big day is ending, it's pretty natural to expect some kick-back in terms of mood.
They are exhausted, probably sugared out to the max, and highly stimulated.
So what can you do to prepare them and you for the inevitable? Here are a few tips:

1. If your kid is an introvert, he/she probably needs some immediate downtime to recover from hours of intensive extroversion.
   Have a new or favorite DVD ready to go, make some hot cocoa.
   Or for active kids, plan to go for a swim or a bike ride.
   Think ahead of time about what type of activity usually helps them re-center themselves and relax.
   
2. For kids who can't get enough, the end of the party signals the end of the fun.
   In this case, think about having a close friend stay after the party to play for a while longer or sleep over (if you can stand it).
   This can help ease the transition from a full house to the monotony of boring old Mom, Dad and siblings.
   
3. Save a few presents from the party or save a family present that you know your kid will be excited about to open after the party.
   If it's something that can immediately engage him or her, all the better.
   
4. Have a special treat planned such as bowling or dinner at a favorite spot.
   Sometimes a change of venue can work wonders.
   
5. Expect some let-down and normalize it for them.
   If they are feeling sad or grumpy, reassure them know that this is all part of the party experience and that they will feel better soon.
   Don't insist that they put on a happy face or be grateful for the great party--they simply may not be capable of it at that moment.
   

One more thing--don't forget to take care of yourself.
Throwing birthday parties can be stressful! Go have a glass of wine and put your feet up or head out to a movie with the family.
The mess can wait.