And they sleep all day?

From The National Sleep Foundation:

FACTS:

• Sleep is vital to your well-being, as important as the air you breathe, the water you drink and the food you eat. It can even help you to eat better and manage the stress of being a teen.
• Biological sleep patterns shift toward later times for both sleeping and waking during adolescence -- meaning it is natural to not be able to fall asleep before 11:00 pm.
• Teens need about 9 1/4 hours of sleep each night to function best (for some, 8 1/2 hours is enough). Most teens do not get enough sleep — one study found that only 15% reported sleeping 8 1/2 hours on school nights.
• Teens tend to have irregular sleep patterns across the week — they typically stay up late and sleep in late on the weekends, which can affect their biological clocks and hurt the quality of their sleep.
• Many teens suffer from treatable sleep disorders, such as narcolepsy, insomnia, restless legs syndrome or sleep apnea.

CONSEQUENCES:

Not getting enough sleep or having sleep difficulties can:

• Limit your ability to learn, listen, concentrate and solve problems. You may even forget important information like names, numbers, your homework or a date with a special person in your life;
• Make you more prone to pimples. Lack of sleep can contribute to acne and other skin problems;
• Lead to aggressive or inappropriate behavior such as yelling at your friends or being impatient with your teachers or family members;
• Cause you to eat too much or eat unhealthy foods like sweets and fried foods that lead to weight gain;
• Heighten the effects of alcohol and possibly increase use of caffeine and nicotine; and
• Contribute to illness, not using equipment safely or driving drowsy.

Notice anything?  I sure do!  Everything known about normal sleep requirements for the average teenager is at odds with the typical high school schedule.  Why is this done to teens?  Because the schools' schedule can't adequately accommodate these needs.  One of the recommended solutions is to start school at a later time, but teens do not have a say in when they can attend school.

Unschoolers (& homeschoolers) are able to get the proper rest required for good physical, mental & psychological health when they are able to go to bed when they are tired & waken when they are ready.  

Does this mean they never get up early?  Of course not!  My children get up early when there is a reason - just like most adults.  How many adults get up early on the weekend or during their vacation "just because"?  Few - because unless they are getting up for a particular reason, they will stay asleep until they are naturally ready to waken.  Kids are no different.  So don't judge the night owls & assume laziness on their part - they are only doing what is natural.