They are said to love music and water, and to be fascinated by mirrors, reflections and plastic. Hand clapping and hand flapping are common, the latter especially when walking or with excitement. Claims that two-thirds of children with Angelman syndrome have autism or pervasive developmental disorder require more extensive investigation. Over excitability, over activity and limited attention span are characteristic in childhood, but become less apparent with age and concentration appears to improve. There are accounts of aggressive behaviour and temper tantrums in some children with Angelman syndrome, but these have not been confirmed in other reports.
Difficulties initiating and maintaining sleep are common.
The children appear to need less sleep than other children, often napping only for short intervals, and sleeping on average five to six hours a night. Severely disrupted nights are typical and parents may report destruction of bedroom furniture during the night. Behavioural techniques can be helpful in managing the sleeping difficulties, possibly in combination with medication. A period of particularly poor sleep sometimes precipitates a bout of seizures. Fortunately, length of sleep seems to increase with age.