Similar effects are commonly seen in people whose

  • No School
  • AA 1
  • 42

This preview shows page 12 - 15 out of 42 pages.

Similar effects are commonly seen in people whose sleep pattern is disrupted due to external factors, such as working regular night shifts (particularly after working regular day shifts in the weeks beforehand). Another example is jetlag which is caused by travel between different time zones. Both shift work disorders and jetlag are very common expressions of circadian rhythm disorders. Humans are not designed to be awake during the night and asleep during the day. People who regularly work night shifts are thought to be at a greater risk of cancer 14 and heart disease 15 . International flight crews are also at elevated risk of cancer, possibly due to repeated disruption of circadian rhythms. Disruption of sleep and circadian rhythms are also documented in people who suffer from bipolar disorder, although it is unclear whether the circadian timer or sleep homeostat is responsible for the underlying sleep disturbances 16 . It has been suggested that changes in a person’s circadian rhythms can act as a trigger for bipolar disorder 17 , particularly mania 18 . Humans are not designed to be awake during the night. People who regularly work night shifts are thought to be at a greater risk of cancer and heart disease.
Image of page 12
‘The machinery is always going. Even when you sleep.’ Andy Warhol
Image of page 13
23 22 We typically pass through four stages of non-REM sleep before beginning REM sleep. In total, non-REM sleep accounts for about 75–80% of total sleep in an average adult. This process is cyclical and during a single night we may experience four or five recurring cycles of non-REM and REM sleep each lasting between 90–110 minutes. Only recently have scientists begun to understand the process, especially since sleep research has been aided by three measurements: 01 Brain wave activity using an electroencephalogram (EEG), which measures electrical activity in the brain. 02 Muscle tone through an electromyogram (EMG). 03 Movement of the eye via an electro-oculogram (EOG). Of these three, the EEG is the most important in helping to differentiate between the different sleep stages. While awake, our brains display a pattern of brainwaves known as beta waves. Beta waves are high in frequency, meaning they occur in quick succession, but they are low in amplitude, meaning they are quite small. Whilst we are awake these waves do not follow a consistent pattern. This makes sense because when we are awake, our brains are often doing a number of different tasks, stimulating the brain in a variety of different ways. When we rest with our eyes closed, our brain wave activity slows down and becomes more synchronised, these brain waves are known as alpha waves. Non-REM stage one The first of the five sleep stages is a form of light sleep, or non-REM stage one sleep. This stage is essentially the bridge between being awake and sleep.
Image of page 14
Image of page 15

You've reached the end of your free preview.

Want to read all 42 pages?

  • Fall '19
  • Sleep Matters

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes
A+ icon
Ask Expert Tutors