The Stirring Sound of Stress

The internal alarm clock. Why we sometimes wake a minute before the alarm.

By Jeff Howe, published on May 1, 1999 - last reviewed on June 4, 2008

Have you ever woken up five minutes before your alarm rings? This mysterious
phenomenon isn't just bizarre coincidence. We are all equipped with our
own internal alarm clocks and, best of all, they even have snooze
buttons.

Jan Born and fellow researchers at the University of Lubeck
in Germany have discovered what may be the first biological evidence for
the curious ability to wake up at will. Anticipating the time you want to
rise seems to trigger the release of hormones normally secreted by the
body in times of stress. About an hour before you've planned to get out
of bed, these secretions increase in preparation for the "stress" of
waking.

In a three-night study, Born and team tucked 15 volunteers into bed
at midnight the first night, and told them they would be woken at 6 a.m.
on one night and 9 a.m. the other two nights.

When the volunteers knew they would be woken at six, levels of the
central stress hormone adrenocorticotropin began rising around 4:30 a.m.
But subjects expecting to wake at nine and rudely awakened at six
experienced no such hormonal surge. Our bodies, in other words, note the
time we hope to begin our day and gradually prepare us for consciousness,
not unlike a snooze button.

But how can we set our own wake up calls? "I am convinced that
eventually there will be a psychological technique to strengthen the
ability to set the internal alarm clock," Born says. Cognitive
self-instruction, in which a person drills himself in his plans for
the next day, may wind the alarm, he says. For now, however, hang on to
that little dream machine beside your bed.