Circadian rhythm sleep disorder in the context of Delayed sleep phase disorder

A sleep disorder, or somnipathy, is a medical disorder that disrupts an individual's sleep patterns and quality. This can cause serious health issues and affect physical, mental, and emotional well-being. Polysomnography and actigraphy are tests commonly ordered for diagnosing sleep disorders.

Sleep disorders are broadly classified into dyssomnias, parasomnias, circadian rhythm sleep disorders, and other disorders (including those caused by medical or psychological conditions). When a person struggles to fall or stay asleep without an obvious cause, it is referred to as insomnia, which is the most common sleep disorder. Other sleep disorders include sleep apnea, narcolepsy, hypersomnia (excessive sleepiness at inappropriate times), sleeping sickness (disruption of the sleep cycle due to infection), sleepwalking, and night terrors.

Solitude, also known as social withdrawal, is a state of seclusion or isolation, meaning lack of socialisation. Effects can be either positive or negative, depending on the situation. Short-term solitude is often valued as a time when one may work, think, or rest without disturbance. It may be desired for the sake of privacy. Long-term solitude may stem from soured relationships, loss of loved ones, deliberate choice, infectious disease, mental disorders, neurological disorders such as circadian rhythm sleep disorder, or circumstances of employment or situation.

A distinction has been made between solitude and loneliness. In this sense, these two words refer, respectively, to the joy and the pain of being alone.

Polysomnography (PSG) is a multi-parameter type of sleep study and a diagnostic tool in sleep medicine. The test result is called a polysomnogram, also abbreviated PSG. The name is derived from Greek and Latin roots: the Greek πολύς (polus for "many, much", indicating many channels), the Latin somnus ("sleep"), and the Greek γράφειν (graphein, "to write").

Type I polysomnography is a sleep study performed overnight with the patient continuously monitored by a credentialed technologist. It records the physiological changes that occur during sleep, usually at night, though some labs can accommodate shift workers and people with circadian rhythm sleep disorders who sleep at other times. The PSG monitors many body functions, including brain activity (EEG), eye movements (EOG), muscle activity or skeletal muscle activation (EMG), and heart rhythm (ECG). After the identification of the sleep disorder sleep apnea in the 1970s, breathing functions, respiratory airflow, and respiratory effort indicators were added along with peripheral pulse oximetry. Polysomnography no longer includes NPT monitoring for erectile dysfunction, as it is reported that all male patients will experience erections during phasic REM sleep, regardless of dream content.

Jet lag is a temporary physiological condition that occurs when a person's circadian rhythm is out of sync with the time zone they are in, and is a typical result from travelling rapidly across multiple time zones (east–west or west–east). For example, someone travelling from New York to London, i.e. from west to east, feels as if the time were five hours earlier than local time, and someone travelling from London to New York, i.e. from east to west, feels as if the time were five hours later than local time. The phase shift when travelling from east to west is referred to as phase-delay of the circadian cycle, whereas going west to east is phase-advance of the cycle. Most travellers find that it is harder to adjust time zones when travelling east. Jet lag is caused by a misalignment between the internal circadian clock and the external environment, and it has been classified within the category of a circadian rhythm sleep disorder, reflecting its basis in disrupted biological timing rather than general travel fatigue.

The condition may last several days before a traveller becomes fully adjusted to a new time zone; it takes on average one day per hour of time zone change to reach circadian re-entrainment. Jet lag is especially an issue for airline pilots, aircraft crew, and frequent travellers. Airlines have regulations aimed at combating pilot fatigue caused by jet lag.

Excessive daytime sleepiness (EDS) is characterized by persistent sleepiness and often a general lack of energy, even during the day after apparently adequate or even prolonged nighttime sleep. EDS can be considered as a broad condition encompassing several sleep disorders where increased sleep is a symptom, or as a symptom of another underlying disorder like narcolepsy, circadian rhythm sleep disorder, sleep apnea or idiopathic hypersomnia.

Some persons with EDS, including those with hypersomnias like narcolepsy and idiopathic hypersomnia, are compelled to nap repeatedly during the day, fighting off increasingly strong urges to sleep during inappropriate times such as while driving, while at work, during a meal, or in conversations. As the compulsion to sleep intensifies, the ability to complete tasks sharply diminishes, often mimicking the appearance of intoxication. During occasional unique and/or stimulating circumstances, a person with EDS can sometimes remain animated, awake and alert, for brief or extended periods of time. EDS can affect the ability to function in family, social, occupational, or other settings. A proper diagnosis of the underlying cause and ultimately treatment of symptoms and/or the underlying cause can help mitigate such complications. According to the National Sleep Foundation, around 20 percent of people experience EDS.