Tools are available to screen and evaluate sleep disorders (Luyster, 2015). Sleep disorders are very common in PwP; they are reported in as many as up to 96% of PwP and have a huge impact on their quality of life (Schrempf, 2014).
Common sleep disorders in PD include insomnia, sleepiness during the day with sleep attacks, restless-legs syndrome (RLS) and REM-sleep behaviour disorder (RBD).
Antiparkinsonian medicines may also cause or aggravate them. Excessive sleepiness leads to difficulty in remaining reasonably awake during the day.
If these symptoms are present before B1 therapy is started, they could be monitored to assess whether B1 is improving them.
As any other symptom, sleep disorders may temporarily increase in severity as a result of B1 “overdose” while searching the right dose during the trial and error phase.
RLS is characterized by an unpleasant urge to move the legs, especially at rest, in the evening and at night. RLS is associated with insomnia symptoms, depression, and several medical conditions.
THE INTERNATIONAL RESTLESS LEGS SYNDROME SCALE (IRLSS) The IRLSS is the most commonly used questionnaire for assessing RLS.
It is a self-report questionnaire with 10 items which collects information on intensity, frequency, severity of RLS symptoms, sleep problems, and their impact on daily life over the past week. It can therefore be used once a week.
It has been found to have “high levels of internal consistency, inter-examiner reliability, test-retest reliability over a 2-4 week period, and convergent validity.” (Restless Legs Syndrome Study Group, 2003).
RBD (REM-SLEEP BEHAVIOUR DISORDER) RBD is also a very frequent condition in PwP. It entails acting one’s dreams, kicking, yelling, getting off the bed at night and may cause injuries to the sufferers and their partners (Schrempf, 2014). It also has prognostic value.
Once RBD is confirmed in a PwP, its frequency can be monitored during the search for the right dose of B1.
Anectodal reports suggest that, in some PwP on B1 right dose, the frequency of RBD episodes may decrease, and in PwP in whom the B1 dose is too high, it can increase as a sign of “overdose”.
RBD1Q for RBD The following single question, to be answered with a “Yes” or “No” (RBD1Q), has been used as a screening tool for RBD and found to have a sensitivity of 93.8% and a specificity of 87.2%: “Have you ever been told, or suspected yourself, that you seem to ‘act out your dreams’ while asleep (for example, punching, flailing your arms in the air, making running movements, etc.)?” (Postuma, 2012).
CONSENSUS SLEEP DIARY This diary helps collect information on time to go to bed, time to fall asleep, number and length of awakenings during sleep, time of final awakening, qualitative rating of sleep quality, and free comments.
PARKINSON’S SLEEP SCALE (PDSS) The PDSS is a simple 15-item questionnaire on nocturnal sleep experience in the past week based on commonly reported symptoms to which the respondent assigns a score based on perceived severity. It can therefore be used once a week.
An extended version of PDSS (PDSS-2), developed to include restless legs syndrome, akinesia, pain, and sleep apnea in addition to nocturnal disturbances, has been validated and found to be a “reliable, valid, precise, and potentially treatment-responsive tool for measuring sleep disorders in PD.” (Trenkwalder, 2011).
ISI (INSOMNIA SEVERITY INDEX) The ISI is a self-report instrument listing 7 items to assess the degree of difficulty in falling asleep, staying sleep, and waking up too early over the past 2 weeks and monitor response to treatment. It can be used every two weeks.
Bastien et al. validated it and concluded that it “is a reliable and valid instrument to quantify perceived insomnia severity” (Bastien, 2001).
PSQI (PITTSBURGH SLEEP QUALITY INDEX) The PSQI enables a general assessment of sleep quality over the past month. It has 19 items. It can then be used monthly. A global PSQI score greater than 5 indicates a poor sleeper.
It yielded a diagnostic sensitivity of 89.6% and specificity of 86.5% in distinguishing good and poor sleepers (Buysse, 1989; Beaudreau, 2012).