From: rdshydur@Athena.MIT.EDU
Message-Id: <9308111942.AA07282@bolognese>
To: zinky@Athena.MIT.EDU
Cc: gardner@faxon.com, istraus@world.std.com, jpbonsen@Athena.MIT.EDU,
        rdshydur@Athena.MIT.EDU
Subject: "Sleeping Until the Crack of Noon" ...
Date: Wed, 11 Aug 93 15:42:08 EDT


(from the "Notes" page of _Technology Review_, Aug/Sep'93, p.80,
reproduced without asking for permission).

Many of us would probably brush off a teenager's desire to
stay up late as an adolescent attempt to resist parental control.
But a new study by researchers at Brown University suggests 
that biological changes associated with the onset of puberty
may be the real cause of the behavior.  A survey of about 500
sixth-grade students revealed a correlation between pubescent 
changes, such as facial-hair growth in boys and menstruation in
girls, and a propensity for being more active later in the day.

Study director Mary Carskadon speculates that melatonin, a light-
sensitive hormone, could be responsible, since it may be involved
in regulating both daily rythms and reproductive cycles.  In
certain animals, the hormone alerts the brain to seasonal changes
by its response to changes in the period of daylight.  For example,
a melatonin signal that spring is imminent means that conditions
are favorable for reproduction and that activities may be extended
a little longer each day.  Similarly, during human puberty,
melatonin has been implicated as a signal to prepare the body for
reproduction.  But the message to extend the day may be getting
passed on as well.

If substantiated, the findings may have implications for the timing
of the school day, says Carskadon.  "The practice of ringing the
opening bell earlier in high school than in junior high, and earlier
in junior high than in elementary school, may run precisely counter
to childrens' biological needs."
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eof;
.