Sure, it can be true, especially if you are new to being released from your real Corporeal body.
In the beginning we seem to use more energy that is necessary. When I "go-out-traveling"
I sleep 1/2 an hour extra for every hour I'm out-there, and I go "out" often.
I like to use the Day Dream format to do my Out-of-Body explorations and I'll take naps. Using
the Remote Viewing mode takes the least amount of extra energy. Using the Astrol form takes
a bit more energy then RV, but not much more. To "go out" in Astral takes the most energy,
because you need to maintain it's solid form.
The activities your "Out-of-Body" form gets involved with makes a difference too. Just observing
uses less energy then making love, and that uses less energy then being involved in fighting
hand against hand, fighting in a war.
One incident in my "travels" I had spent time with a family of ancestors [30,000BC+-] and
participated in their 2 hour "Blessing-Of-The-Fields" ceremony. After the Blessing there was
a village celebration, and everyone was interested in meeting someone from their future.
I made sure to get extra sleep before hand, because this party could go on all night.This was a
picture-telepathic society, so I needed extra empathy shielding even as I controlled my thoughts.
The clothing to be warn was a floor length linen Tunic with stripes of the family color, and a wide
red leather belt around me and across my chest to support the short sword on my back. I planned
to manifested myself only as the upper half of my body, to conserve energy. I made no secret of
that fact. During the celebration, they danced a variety of the Shodish
[?sp?] very similar to a polka. My partners, ha,ha,ha, would reach down behind me to see where I
stopped being.. When I returned "Home" I slept for 10 hours.