This is a multicenter home-based medical device intervention study, with prospective validation of the wearable seizure detection device (Nightwatch) and retrospective validation of remote sensors (video and audio detection) in children. The investigators will also perform a feasibility and utility analysis of Nightwatch.

Various remote and wearable sensor devices have become available for the detection of potentially dangerous seizures, with limited impact on epilepsy care so far. Both the investigator's remote and wearable seizure detection devices (SDDs) have been extensively tested and proven highly sensitive. Yet the home performance in children, an important target population, had been insufficiently studied.

Objective: 1. To test the performance of the wearable SDD (Nightwatch) prospectively and the remote SDD (automated video and audio analysis) retrospectively in children in a family home setting. 2. To assess the feasibility, cost-effectiveness and cost-utility of Nightwatch in children.

Study design: A multicenter home-based medical device intervention study with prospective validation of our wearable SDD.

Study population: 60 children (ages 4-16 years) with refractory epilepsy (≥1 major nocturnal seizure per week) recruited from the outpatient clinics of one of the participating epilepsy centers (Stichting Epilepsie instellingen Nederland (SEIN), Academic Centre of Epileptology Kempenhaeghe (Kempenhaeghe), University Medical Center Utrecht (UMCU)).

Intervention: Phase I: Two months of baseline (usual care); Phase 2: Two months of nocturnal seizure monitoring at home, using Nightwatch and the remote SDD.

Main study parameters/endpoints: The diagnostic performance of Nightwatch and the remote SDD algorithms, i.e. sensitivity, positive predictive value, false alarm rate and % time with uninterrupted signal output. The investigators will evaluate feasibility of Nightwatch through surveys on quality of life, sleep, parental strain, interviews with parents/guardians and neurologists, and a value sensitive design group session. The investigators will also perform a cost-effectiveness and cost-utility analysis by medical consumption and costs questionnaires.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Implementing SDDs will not pose any direct or substantial risk. Study participation can be a burden though, due to impact of the devices on privacy, number of false alarms and time spent on the questionnaires and interviews. Application of the SDDs, however, might offer better insight into the actual number of nocturnal seizures in a child, change in medical management and facilitate appropriate interventions in major motor seizures. If reliable, SDDs may improve the night rest of both patient and parents/guardians.

Inclusion Criteria:

• Age 4-16 years
• Diagnosis of refractory epilepsy with ≥1 major nocturnal seizure per week.
• Treated at one of the following epilepsy centers: SEIN, Kempenhaeghe or UMCU.
• Written informed consent by legal representatives (mostly parents) and also by the subject when aged ≥12 years and capable of signing informed consent.

Exclusion Criteria:

• Intensive non-epileptic movement patterns such as severe choreatiform movements, intensive sleep walking, or frequent night terrors (> 1/week).
• Minor motor seizures only, i.e. non-generalized or short (< 10 sec.) tonic seizures or isolated myoclonias that are self-limited and do not require intervention.
• Presence of a pacemaker or cardiac arrhythmias that may generate false alarms (e.g. supraventricular tachycardia).
• Inability to comply to the trial procedure.
• Skin characteristics (e.g. tattoo) that may affect photoplethysmography and thereby influence performance of the Nightwatch.
• Dependence on another SDD (e.g. Emfit or saturation monitor). Simultaneous use of a baby phone (or other types of microphones) is permitted.
• Subjects who are not sleeping alone in the bed (i.e. co-sleeping in the parents'/guardians' bed influences the remote SDD). Subjects and parents/guardians are not allowed to change their sleeping habits for the duration of the study only.

Principal investigators will share necessary information on participants and enrollment.