This study will use polysomnography, alongside other methodologies such as questionnaires, actigraphic measurements and salivary melatonin samples used in previous studies to investigate sleep quality in patients with i) localized, locally advanced or metastatic hormone sensitive prostate cancer or ii) with full-resected early (stage I-III) epithelial breast cancer. The measurements will be taken before androgen deprivation therapy (ADT - for prostate cancer patients) or endocrine therapy (for breast cancer patients) is initiated, at 6 months and some measures again at 12 months.The groups, defined by cancer type and whether or not treatment includes ADT / endocrine therapy, will be compared to see if there are differences in the prevalence of the lowered sleep quality in the groups.

The main outcomes of this pilot study can be summarised as:

• Using a previously unused methodology to assess whether ADT / endocrine therapy may negatively affect patterns of sleep quality
• Identifying sleep micro/macrostructure changes in prostate cancer patients receiving ADT / endocrine therapy
• Comparing the novel methodology with results obtained previously through standard methods
• Providing statistical underpinnings, such as sample size calculations, for a full interventional trial
• Highlighting the most appropriate non-pharmaceutical interventions to be tested in the full interventional trial

Inclusion Criteria for prostate cancer patients:

• Written infor med consent according to International Conference on Harmonisation (ICH)/Good Clinical Practice (GCP) regulations before registration and prior to any trial specific procedures
• Histologically proven adenocarcinoma of the prostate
• Eastern Cooperative Oncology Group performance status 0-2
• Adult male patient > 18 years of age, no upper age limit
• Localized prostate cancer, locally advanced hormone-sensitive prostate cancer (HSPC) or metastatic hormone-sensitive prostate cancer (mHSPC)
• ADT recipients are required to be scheduled to start ADT as standard of care (SOC) for metastatic or locally advanced prostate cancer
• Scheduled to receive ADT treatment as SOC for > 6 months in combination with radiotherapy or oral AR-targeted systemic treatment as prescribed by the treating physician or radiotherapy alone

Exclusion Criteria for prostate cancer patients:

• Histology with predominant small cell prostate cancer
• Any previous treatment with ADT or oral AR-targeted agent (exception for short course anti-androgens - disease flare)
• Have not received systemic treatment for any other cancer within the last 12 months
• Active secondary malignancy that requires systemic therapy
• Any clear contraindications present against treatment with ADT
• Presence of sleep apnea syndrome, Apnea Hypopnea Index (AHI) >15 at baseline
• Body mass index (BMI) > 35 at baseline
• Severe respiratory disorders (asthma, Chronic obstructive pulmonary disease) at baseline
• Severe cardiovascular disease or severe cardiovascular event < 6 months
• History of stroke or other neurologic chronic illnesses < 6 months
• Have demonstrated impaired mental status
• History of brain tumours, presence of brain metastases or previous cranial irradiation
• Night shift workers
• Excessive lifestyle: massive coffee intake at night, regular excessive cigarette and alcohol consumption in the evening
• Unhealthy sleep hygiene
• Nocturia (the urgent need to urinate more than 2 times during the main sleep period at night) at baseline
• Present diagnosis of depression or psychiatric illness pharmacologically treated
• Diagnosis of insomnia and chronic intake of hypnotic medication at baseline
• Chronic intake of medications that are known to induce sleep disturbance (antihistamines of first generation, cortisone intake > 25 mg/day)
• Any diagnosed condition that causes known sleep disturbance

Inclusion criteria for breast cancer patients

• Written informed consent according to International Conference on Harmonisation (ICH)/Good Clinical Practice (GCP) regulations before registration and prior to any trial specific procedures
• Women with full-resected early (stage I-III) epithelial BC, ductal carcinoma in situ or lobular carcinoma in situ, without evidence of residual disease
• Eastern Cooperative Oncology Group performance status 0-2
• Adult female patient ≥ 18 years of age, no upper age limit
• Proven postmenopausal status (defined by absence of menstruation for at least 6 months and/or level of estradiol <40 pg/ml, or bilateral oophorectomy or ovarian irradiation for suppression of ovarian function)

Exclusion criteria for breast cancer patients

• Non-epithelial BC or BC with mixed epithelial and non-epithelial histology
• Previous chemotherapy at any time, in treatment with ET at not standard dosage
• Have received systemic treatment for any other cancer within the last 12 months
• Active secondary malignancy that requires systemic therapy
• Presence of sleep apnea syndrome, Apnea Hypopnea Index (AHI) >15 at baseline
• Body mass index (BMI) > 35 at baseline
• Severe respiratory disorders (asthma, Chronic obstructive pulmonary disease) at baseline
• Severe cardiovascular disease or severe cardiovascular event < 6 months
• History of stroke or other neurologic chronic illnesses < 6 months
• Have demonstrated impaired mental status
• History of brain tumours, presence of brain metastases or previous cranial irradiation
• Night shift workers
• Excessive lifestyle: massive coffee intake at night, regular excessive cigarette and alcohol consumption in the evening
• Unhealthy sleep hygiene
• Nocturia (the urgent need to urinate more than 2 times during the main sleep period at night) at baseline
• Present diagnosis of depression or psychiatric illness pharmacologically treated
• Diagnosis of insomnia and chronic intake of hypnotic medication at baseline
• Chronic intake of medications that are known to induce sleep disturbance (antihistamines of first generation, cortisone intake > 25 mg/day) or any diagnosed condition that causes known sleep disturbance

i) Patients with localized, locally advanced or metastatic hormone-sensitive prostate cancer receiving standard of care treatment (including radiotherapy with or without androgen-deprivation treatment (ADT) or ADT alone +/- androgen receptor targeted agent) dependent on disease stage ii) Patients with full-resected early (stage I-III) epithelial BC, ductal carcinoma in situ or lobular carcinoma in situ, without evidence of residual disease