If indicated, consider other investigations such as:
Sleep study if there are symptoms such as excessive daytime sleepiness that might suggest sleep disorder such as sleep apnea, restless legs, periodic limb movement disorder, etc. Lausanne NoSAS score for sleep apnea.pdf
CT/MRI if there are focal neurologic symptoms suggesting focal lesions
Rule out main psychiatric differential diagnoses such as:
A. Five (or more) of the following symptoms have been present during the same 2-week period and represent a change from previous functioning; at least one of the symptoms is either (1) depressed mood or (2) loss of interest or pleasure.
Note: Do not include symptoms that are clearly attributable to another medical condition.
Depressed mood most of the day, almost every day. Mood is classically sadness but can also include emptiness, hopelessness or irritability.
Markedly diminished interest or pleasure in all or almost all activities most of the day nearly every day.
Significant weight loss when not dieting or weight gain.
Inability to sleep or oversleeping nearly every day.
Psychomotor agitation or retardation nearly every day.
Fatigue or loss of energy nearly every day.
Feelings of worthlessness or excessive or inappropriate guilt (which may be delusional) nearly every day.
Diminished ability to think or concentrate, or indecisiveness, nearly every day.
Recurrent thoughts of death (thoughts such as wanting to die, not just fear of dying), recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide.
B. Symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning
C. The episode is not due to the effects of a substance or to a medical condition
D. The occurrence is not better explained by schizoaffective disorder, schizophrenia, schizophreniform disorder, delusional disorder, or other specified and unspecified schizophrenia spectrum and other psychotic disorders
E. There has never been a manic episode or a hypomanic episode