Types of circadian rhythm sleep disorder
Jet lag can cause symptoms like excessive sleepiness and a lack of alertness during the day. It happens to people who travel across time zones.
Shift work sleep disorder can affect people who work different shifts or often work through the night.
Delayed sleep phase syndrome is a disorder of sleep timing that makes people fall asleep very late, and struggle to wake up on time in the mornings.
Advanced sleep phase syndrome causes afternoon and early evening sleepiness, falling asleep early and then waking up earlier in the morning. People go to bed much earlier than is normal, and then can’t get back to sleep when they wake up in the early hours of the morning.
Non 24-hour sleep wake disorder is a combination of advanced and delayed sleep disorders which in effect makes you live, for example, a 25-hour day. People with this disorder can’t set a sleep pattern no matter how hard they try. Sometimes they aren’t tired so they fall asleep late and wake up late, and other times fall asleep early and wake up too early.