Important factors in these changes are the biological rhythms, and, more specifically, the circadian rhythms generated by the suprachiasmatic nucleus (SCN). When people travel across multiple time zones or work rotating shifts, they can experience disruptions of their circadian cycles that can lead to insomnia, sleepiness, and decreased alertness.

If people go extended periods of time without sleep, they will accrue a sleep debt and potentially experience a number of adverse psychological and physiological consequences States of consciousness vary over the course of the day and throughout our lives.

consciousness — awareness of internal and external stimuli. sleep — state marked by relatively low levels of physical activity and reduced sensory awareness that is distinct from periods of rest that occur during wakefulness. suprachiasmatic nucleus (SCN) — area of the hypothalamus in which the body’s biological clock is located. insomnia — consistent difficulty in falling or staying asleep for at least three nights a week over a month’s time.