Jet lag
The severity of jet lag symptoms is directly related to the number of time zones crossed by a flight. The symptoms of jet lag include:
Daytime sleepiness

Nighttime alertness (insomnia)

Loss of appetite and other

Gastrointestinal dysfunction

Mood disturbances

Difficulty concentrating or focusing
Illness
The changes in sleep rhythm depend on the type and severity of illness. Sometimes the improvement in a psychiatric disease is gauzed by the changing sleep patterns.
Shift working
The main complaint for people with shift work sleep disorder is excessive sleepiness. Other symptoms include:

Insomnia

Disrupted sleep schedules

Reduced performance

Difficulties with personal relationships

Irritability/depressed mood.