As parents become more and more erudite about Autism, and understanding how to treat our children, 'Time' seems to become more and more valuable and there seems to be less of it.  Parents have to learn to turn their attention toward caring for themselves....you know the 'adage'- "put your own O2 mask on first, then assist the child". 
For parents of Autistic children, the older they get, the longer you've been focused and working daily to help them, treat them, and care for them- as well as your other children. 
So by the time you've got teenagers, the toll the care time will have taken on you will likely feel like it's been much longer than it actually has.  You've dedicated an incredible amount of your time to learning, seeking the advice of experts, talking to other parents, reading everything you have access to, and researching the science and medical information that comes out on a near daily basis. 
There are many issues you'll face by this time in your life.  
One of the primary things you'll need to manage is your 'Time'....as it'll feel like it's shrinking and you'll feel like you're trying to cram more and more into that little bit of time as possible.  You'll likely be losing time sleeping to catch up on all of the things you weren't able to get to during the day. 
So you're going to start to feel like you're burning out.  Especially early in the day.  When you wake up at 5am and then you go every moment without a single second to yourself,...you're going to need to plan your days carefully. 
You may notice that you start feeling tired by the time everyone is finishing up their dinner.  When this happens; there are two things you can do to prepare and take advantage of your time.  First- prioritize your day the night before.  Write down the top three most important things you need to get done in a journal before you go to bed the night before.  This will help you stay on task and know that you'll be able to accomplish the things that are most important to you.  Second- understand the value of a short 'catnap'. Discover when you feel the most tired in your day, and then plan a half hour to a one hour resting period into that time.  There are many activities you can set your children up with prior to laying down for some rest.  During school time- your rest time could be a good time for your children to take some 'down' time.  As we do in our home.  We have a list of activities the children can choose from, or they can even use the time (which is about 4pm to 4:30pm or 5pm) to sit on their beds for some 'much needed' quiet time, and play iPods, or their Ninendo, lie on their beds and watch a DVD or even just use the time to read books of their choice.  
You'll find that your children will get used to this time period and begin determining how they wish to spend the 'down time'....and as they become more aware of "Time" itself, they'll be able to understand that it is "Quiet Time".  And even older kids- and adolesence will appreciate having this time to themselves.  Especially following a long day at school.  They will settle right in and sometimes you can plan ahead by taking them to the bookstore and buying books for the upcoming week.  
In many countries a daily "Period of Rest" is understood as a crucial and useful element of the day.  Particularly for those who work long hours, just as we do in the US.  Unfortunately most people don't honor the cues of fatigue from their bodies and simply 'push' through the fatigue until late at night.  Science has actually shown us that 'pushing' ourselves to complete activities when we are very tired actually defeats the purpose, as we aren't able to do our best work and typically have to either re-do the activity or start over at another time. As well, science shows us that when we are overly fatigued we lack patience, feel more fearful and aren't able to reason as we normally do. 
Realize that raising children with Autism causes much more daily tiredness than most adults experience.  Honor your life, honor your body and honor yourself by allowing yourself and your children even just an hour of 'short rest' to make the early part of your day more productive, and the later part of your day more comfortable for you and your children.