Should I leave the light on?

Pete Stephenson wrote:

In article ,
"Daniel Morrow" wrote:


Fish need to sleep too or else they get stressed out which after a
prolonged period of light can cause the fish to get sick and perhaps pass
away.


I've always been curious how fish sleep, particularly if the current in
the tank is constant. My pleco, I can understand -- he just sucks onto
the log or the glass, and he's anchored.

The danios and tetras have no such luxury. I would imagine if they
became fully unconscious, they'd drift with the current and bump into
things.

How are they able to sleep without becoming fully motionless and thus
bumping into things?


Recently, a 15 year old girl climbed to the top of a crane, walked
across a narrow beam and then curled up upon the concrete counterweight
while remaining fast asleep. Being fully unconscious doesn't seem like
a prerequisite for having a very good night's sleep. Humans are
constantly tossing and turning in the lighter phases of the sleep
pattern without being conscious.

I'd guess that the fish put themselves into some sort of autopilot mode.

Nikki