Shift work sleep disorder affects people who frequently experience jet lag, either from travel, or by shifting their work or sleep schedules frequently. Such recurrent interruption of sleep patterns may result in result in insomnia or excessive sleepiness. Night owls (people who stay up primarily at night) may also experience sleep problems because the body's circadian rhythms control the release of melatonin and other hormones in response to daylight patterns.

See also

• Human factors
• Human reliability
• Modafinil
• Seasonal affective disorder (SAD)