Circadian Rhythm
Jordynn Willer
Jet Lag
Most people's circadian rhythm becomes off track when they fly. This is called jet lag. Jet lag consists of symptoms that include excessive sleepiness and a lack of daytime alertness in people who travel across time zones.
Photo: http://i1.mdzol.com/files/image/587/587915/551e254b04b6a.jpg
Nocturnal Animals
Nocturnal animals have an internal clock that's adapted to night time. Diurnal animals are animals adapted to being awake during the day and asleep at night. Nocturnal animals are just the opposite.
Fruit Flies
A fruit fly's internal clock can be reset by vibration. The circadian rhythm of a fruit fly is not only set by light and temperature but also by mechanical stimuli.
Migration
Photo: https://stinkyspikes.wordpress.com/2009/10/08/do-durian-plants-sleep-at-night/
Plants
Photo: https://stinkyspikes.wordpress.com/2009/10/08/do-durian-plants-sleep-at-night/
Sources
http://sleepfoundation.org/sleep-topics/sleep-drive-and-your-body-clock
http://circadiana.blogspot.com/2005/12/clocks-migration-and-effects-of-global.html
http://www.nigms.nih.gov/Education/Pages/Factsheet_CircadianRhythms.aspx
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1425852/
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Circadian.html