The control comparator will receive a sham intervention in the form of a non-weighted blanket as an add on to usual care. Participants will be asked to choose one out of two different sham blankets.

Usual treatment as part of standard care for children with ADHD, which can consist of sleep hygiene, psychoeducation, cognitive behavioral theory, medications such as melatonin or ADHD medication.

Sleep onset latency (SOL) refers to the period of time between turning lights out to go to sleep and falling asleep. SOL will be measured using actigraphy which includes a button that should be pressed by a caregiver when the lights are turned off. SOL will be reported as minutes per day.

Wake after sleep is defined as number of minutes scored as wake during sleep period and will be measured using actigraphy.

Sleep efficiency (SE) is measured using actigraphy and is the actual sleep time expressed as a percentage of the total time in bed (the time elapsed between "lights out" and "get up time"). SE will be reported as minutes per day.

ADHD core symptoms will be measured with Attention Deficit Hyperactivity Disorder Rating Scale (ADHD-RS) parent version. It is a 26-item questionnaire including the 18 original ADHD-RS-IV items supplied with 8 conduct problem items. All items are rated on a 4-point Likert scale (0-3), where 0 represents never or rarely, 1 is sometimes, 2 is often, and 3 is very often. From the item scores, a total score ranging 0-78 will be calculated. Further, three sub-scores will be calculated; inattentive scale: range 0-27, hyperactive/impulsive scale: range 0-27, and conduct scale: range 0-24.

Changes in parental stress is measured by the Parental Stress Scale (PSS). The PSS is an 18-item questionnaire assessing parents' feelings about their parenting role, exploring both positive aspects (e.g. emotional benefits, personal development) and negative aspects of parenthood (e.g. demands on resources, feelings of stress). Parents can agree or disagree in terms of their typical relationship with their child or children. Responses are scored as follows: strongly disagree, disagree, undecided, agree, strongly agree. To compute the parental stress score, items 1, 2, 5, 6, 7, 8, 17, and 18 should be reversely scored as follows: (1=5) (2=4) (3=3) (4=2) (5=1). The item scores are then summed. Parental stress scores range from 18 to 90, with lower scores indicating lower levels of parental stress.

Child quality of life will be measured using The World Health Organisation- Child Well-Being Index (WHO-5). The WHO-5 Child Wellbeing Index is a simple self-reported measure of children's psychological wellbeing. The tool consists of five statements describing a positive state. The child is asked to say how often they felt that way during the past two weeks, by selecting one of the following options: All the time, Often, Sometimes, Rarely or Never.

Number of participants with adverse events (AE).

Number of participants with serious adverse events (SAE).

Assessed by health economic aspects, such as quality-adjusted life year (QALY) and productivity loss among caregivers.

Functioning impairment will be measured using Weiss Functional Impairment Rating Scale (WFIRS-P). The WFIRS-P is a 50-item scale assessment tool where caregivers rate the impact of their child's emotional or behavioural problems in the previous month on six separate domains: (A) Family (ten items); (B) School and learning; (C) Life skills; (D) Child's self-concept; (E) Social activities; and (F) Risky activities. Each item is rated on a four-point scale from 0 ('never or not at all') to 3 ('very often or very much') or rated as 'not applicable'. The instrument uses a likert scale such that any item rating 2 or 3 is clinically impaired. The mean of all scored items for each domain will be calculated. Furthermore, a single overall WFIRS-P score will also be calculated as the average of the six domain scores.

ADHD core symptoms will be measured with Attention Deficit Hyperactivity Disorder Rating Scale (ADHD-RS) parent version. It is a 26-item questionnaire including the 18 original ADHD-RS-IV items supplied with 8 conduct problem items. All items are rated on a 4-point Likert scale (0-3), where 0 represents never or rarely, 1 is sometimes, 2 is often, and 3 is very often. From the item scores, a total score ranging 0-78 will be calculated. Further, three sub-scores will be calculated; inattentive scale: range 0-27, hyperactive/impulsive scale: range 0-27, and conduct scale: range 0-24.

Parental stress is measured by the Parental Stress Scale (PSS). The PSS is an 18-item questionnaire assessing parents' feelings about their parenting role, exploring both positive aspects (e.g. emotional benefits, personal development) and negative aspects of parenthood (e.g. demands on resources, feelings of stress). Parents can agree or disagree in terms of their typical relationship with their child or children. Responses are scored as follows: strongly disagree, disagree, undecided, agree, strongly agree. To compute the parental stress score, items 1, 2, 5, 6, 7, 8, 17, and 18 should be reversely scored as follows: (1=5) (2=4) (3=3) (4=2) (5=1). The item scores are then summed. Parental stress scores range from 18 to 90, with lower scores indicating lower levels of parental stress.

Child quality of life will be measured using The World Health Organisation- Child Well-Being Index (WHO-5). The WHO-5 Child Wellbeing Index is a simple self-reported measure of children's psychological wellbeing. The tool consists of five statements describing a positive state. The child is asked to say how often they felt that way during the past two weeks, by selecting one of the following options: All the time, Often, Sometimes, Rarely or Never.

Assessed by health economic aspects, such as quality-adjusted life year (QALY) and productivity loss among caregivers.