**5.1 Advanced sleep-wake phase disorder (ASWPD)**

ASWPD is a clinical diagnosis and should be suspected in individuals who have a history of early sleep onset and wake times. It is important to obtain a detailed sleep history that addresses sleep patterns, napping habits, and daytime symptoms of sleepiness, cognitive changes, or mood changes. Targeted questions should be asked about difficulty falling or staying asleep and sleep quality both during the patient's current schedule and during times when he/she has followed the preferred schedule. Obtaining collateral history from a bed partner is often useful.

Patients with suspected ASWPD should keep a sleep log for at least 7 days, preferably 14 days, including both weekdays and weekends (**Figure 1**). Actigraphy is helpful to supplement the sleep diary, especially if the history is unreliable. Melatonin levels, through salivary or plasma sampling, may show early melatonin onset or earlier phase of melatonin metabolite excretion via urinary 6-sulfatoxymelatonin, although these tests are not widely available for clinical purposes [2, 3, 9].

### **5.2 Delayed sleep-wake phase disorder (DSWPD)**

DSWPD is a clinical diagnosis and should be suspected when individuals report consistent bedtime and wake times that are significantly later than social norms. Bedtimes are often more informative than wake times, which are usually dictated by social or work/school obligations. It is also helpful to ask about sleep patterns during weekends, and during unrestricted periods such as vacations, when patients are able to sleep based on their own circadian preference (**Figure 2**). Sleep logs of at least 7 days, including both school/workdays and weekends, are needed to identify specific patterns [9]. It is important to inquire about other social factors, such as caffeine use later in the day, or excessive use of light-emitting devices before bedtime, which can also delay sleep onset.

Wrist actigraphy is another means of obtaining more quantitative data [9]. If the actigraph has a photo sensor it can provide information about the correlation between an individual's light exposure and sleep time. Polysomnography is not typically indicated, unless there is clinical suspicion for another comorbid sleep disorder, such as sleep-disordered breathing. Salivary melatonin assays are available; however, these assays are used primarily as research tools and not for clinical diagnosis.


#### **Figure 1.**

*This 14-day sleep diary of a patient with advanced sleep–wake phase disorder (ASWPD) depicts an early sleep onset (7-8 pm) and early wake time (3-4 am). The total duration of sleep time (shaded box) remains normal at 7-8 hours. Individuals with ASWPD usually do not have symptoms if they are allowed to sleep per their preferred schedule; however, when tasked with staying up later than their usual bedtime, they can have significant difficulty. This circadian rhythm is more prevalent in older adults who may not have the same work or school obligations ("ret" represents "retired") that can contribute to other circadian rhythm disorders, such as delayed sleep–wake phase disorder.*

#### *Circadian Rhythm Disorders DOI: http://dx.doi.org/10.5772/intechopen.99816*

#### **Figure 2.**

*This 14-day sleep diary of a patient with delayed sleep–wake phase disorder (DSWPD) depicts variable sleep depending on the day of the week. The upwards arrow indicates "time in bed" while the downwards arrow indicates "time out of bed". The shaded area represents sleep time of the patient. For example, in this diagram, the individual goes to bed between 9 and 10 pm on school days but is not able to sleep until 2-3 am. Due to his fixed school start time, he has to get out of bed between 6 and 7 am, leaving only 4-5 hours of sleep time (shaded box). However, on weekends (Friday and Saturday nights), he goes to sleep at his desired time of 2-3 am and wakes up at his desired time between 1 and 2 pm, accounting for a total sleep time of 10-11 hours. This variation in sleep pattern, based on day of the week, is classic for DSWPD, and results in the symptoms described by those with this condition.*

#### **5.3 Irregular sleep-wake rhythm disorder (ISWRD)**

The diagnosis of ISWRD is made by clinical history, with supplemental information from wrist actigraphy. There must be a reported chronic or recurrent pattern of irregular sleep and wake episodes throughout a 24-hour period, with a minimum of 3 cycles occurring during that time (**Figure 3**). A sleep log, and/or actigraphy must document these cycles for at least 7 days (preferably 14 days), and symptoms must be present for at least 3 months [9].

Polysomnography is not usually indicated, unless there is concern that the sleep disturbance is better explained by another disorder (e.g., a sleep-related breathing disorder).

#### **5.4 Non-24 sleep-wake rhythm disorder (N24SWRD)**

Sleep diary and actigraphy are important in confirming a non-entrained sleep pattern and will also show a gradual drift of onset and offset of the sleep– wake rhythm (**Figure 4**). In order to appreciate the drift, this data should be obtained for at least 2 weeks, and symptoms should be present for at least 3 months [9].

Other measurements such as continuous core body temperature or serial measurements of melatonin can be confirmatory as they also exhibit a similarly non-24-hour drifting rhythm. However, these procedures are not required to make the diagnosis of N24SWD.

Attention should be paid to distinguish N24SWD from DSWPD, as these patients can display a similar evening phenotype and up to 25% of N24SWD are often initially misdiagnosed as DSWPD [2, 3, 9].

#### **Figure 3.**

*This 14-day sleep diary of a patient with irregular sleep-wake rhythm disorder (ISWRD) depicts an irregular pattern of sleep throughout each 24-hour period. During each day, there are at least 3 sleep cycles occurring in a recurrent, but irregular fashion. The total sleep duration (shaded box) is usually normal for an individual's age, however there is no clearly defined pattern. This disorder is more prevalent in older individuals and in those with dementia.*

#### **Figure 4.**

*This 14-day sleep diary of a patient with non-24 sleep–wake phase disorder (N24SWPD) depicts a gradual drift in onset and offset of the sleep duration (shaded box), usually by 30 minutes each day. In order to best appreciate this drift, a sleep diary or actigraphy should be obtained for at least 2 weeks, and ideally more if possible. This circadian rhythm disorder is most prevalent in individuals who are blind.*

#### **5.5 Shift work sleep-wake disorder (SWD)**

SWD is best assessed through careful sleep history and sleep diary. Particular attention should be paid to a patient's occupation, history with shift work disorder with prior jobs, and impaired task performance at work. Factors specific to the patient's home environment (i.e. lack of dedicated dark space for sleeping, noise levels during the day, etc.) can further reduce the likelihood that the patient can obtain restorative sleep. The clinical history should also inquire about features of other comorbid sleep, medical, and mental disorders. A sleep diary should be obtained for at least 2 weeks and should capture both work and non-work days [9]. Validated questionnaires, such as the Insomnia Severity Index and Epworth Sleepiness Scale, can be used but are not required to diagnose SWD.

#### *Circadian Rhythm Disorders DOI: http://dx.doi.org/10.5772/intechopen.99816*

Wrist actigraphy, especially when performed with an actigraphy that includes a photosensor, can better quantify sleep duration. There is no need for polysomnography unless there is a clinical suspicion for a comorbid sleep disorder, such as a sleep-related breathing disorder. Melatonin sampling is done in research settings, but is not routinely used in the clinical setting.
