Sleep disorders related to biological clock disturbance.

What is the biological clock?

The "master clock" that controls circadian rhythms consists of a group of nerve cells in the brain (in the hypothalamus) called the suprachiasmatic nucleus, (SCN), it regulates your circadian rhythm.

What are circadian rhythms? And how do they affect your sleep?

Circadian rhythms are physical, mental and behavioral changes that follow a roughly 24-hour cycle; it influences sleep-wake cycles, hormone release, body temperature and other important bodily functions. The brain relies on “outside” influences called ‘zeitgebers’ to keep you on a normal schedule. The most obvious zeitgeber is sunlight. Other zeitgebers are ambient temperature, sleep, social contact, physical activity, and even regular meal times. They all send “timekeeping” clues to your brain, helping keep your circadian rhythm running on schedule.

What is the Circadian Rhythm Disruption?

Any time that our normal 24-hour circadian rhythm is altered or interrupted, it will have physiological and behavioral impacts. This is known as circadian rhythm disruption, which will lead to different type of sleep disorders including:

Delayed Sleep Phase Syndrome: some people find that it is difficult to fall asleep before 2:00 am and that they have trouble waking up in the morning (they like to wake up after 10 am) .this problem is very common in young adults and can interfere with school or college schedule.

Advanced Sleep Phase Syndrome: This is a disorder where sleepiness occurs well before the desired sleep schedule. A person feels the urge to go to sleep between in early afternoon around 6:00 and 8:00 p.m. and wakes up too early between 2:00 and 3:00 am. And this is more common among older adults.

Irregular Sleep-Wake RhythmThis sleep disorder applies to people who do not have a regular sleep pattern and who often have changing sleep periods and irregular times of alertness and sleepiness.

Shift Work Disorder: shift workers are those who work nontraditional hours such as night shifts or rotating shifts. They may not get the same amount of sleep during the day, they may have problems adjusting to sleep schedule, feel less energetic and struggle with focusing,

Jet lag: occurs when travelers pass through different time zones, your body's clock will be different from your wrist watch. For example, if you fly in an airplane from New York to Dubai, you "lose" 8 hours of time. So when you wake up at 8:00 a.m., your body still thinks its 12:00 midnight. Making you feel groggy and disoriented. Your body's clock will eventually reset itself, but this often takes a few days.

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