A Novel Approach to Manage Symptoms of Narcolepsy and Idiopathic Hypersomnia

Inclusion Criteria: * Evidence (from multiple sleep latency test, 24-hour polysomnography, or actigraphy) of diagnosis of narcolepsy type 1, narcolepsy type 2 or idiopathic hypersomnia that meets ICSD-3 criteria. * For the NT1 subtype, patients must have been screened positive for the HLA DQB10602 genotype. * Body mass index \>18.5 kg/m2 * 18 years or over * Be willing to be involved in dietary change that may include animal protein and fat. * Be willing to monitor ketones via finger-prick and urinary dipstick. * Habitual diet is a standard diet consuming a moderate or high carbohydrate level (defined for the study as above 130g carbohydrate/day). * Willingness to provide informed consent and willingness to participate and comply with the study requirements. * Access to a computer, laptop, tablet, or smartphone and stable internet access. * Proficient comprehension of English language (able to independently read information sheet) and availability of a support person during consultations if English comprehension is challenged. Exclusion Criteria: * Body mass index \<18.5 kg/m2, history of an eating disorder with an EDE-Q score greater than 3. * Participants who have sustained significant weight loss in the last 3 months (\>5% change in total body weight). * Previous bariatric surgery or current prescription of weight loss medication. * Diagnosis of unstable psychiatric disorders (excluding anxiety or depression). * Cognitive impairment that limits ability to understand the study requirements or provide informed consent. * Physical impairment that limits ability to meet the study requirements. * Non-English speaking and inability to read the Participant Information Sheet. * No access to stable internet and device on which to participate in telehealth consultations and complete study questionnaires. * Person lactating, pregnant or of childbearing potential who are not willing to avoid becoming pregnant during the study period. * Habitual diet is currently low carbohydrate/ketogenic (defined for the study as \<130g carbohydrate/day based on screening 24 food hour recall). * Habitual diet excludes animal products (e.g. Vegan diet). * Laboratory parameters that may indicate alternate catalyst for hypersomnolence in the opinion of the study physician, including abnormal: full blood count, thyroid function, Epstein-Barr Virus, erythrocyte sedimentation rate, cortisol, antinuclear antibodies, extractable nuclear antigen test, positive rheumatoid factor, Antistreptolysin O positive, Iron studies or multiple biochemistry panel. * Participants who have changed their medication prescription or dose within the preceding 4 weeks. * Participants with inherited metabolic disorders, prior history of hypoglycaemia or insulinoma * Participants with insulin dependent Type 1 or Type 2 diabetics prescribed insulin which may interfere with the participant's ability to meet the study requirements. * Participants with uncontrolled medical conditions or patients with significant medical co-morbidities who in the opinion of the study physician, would be at risk of adverse health consequences due to the study intervention (e.g. poorly controlled type 2 diabetic patients who are not prescribed insulin) * Current cancer diagnosis (excluding skin cancers or benign cancers) * Current active enrolment in a pharmaceutical or intervention based clinical trial or participant who may have received an investigational new drug within the last 12 weeks.