An alternative option to duvets and electric blankets is a weighted blanket.

Brentfords Weighted Blanket 8kg for Adults Therapy Anxiety Autism Insomnia Calming Stress Relief with Micro Glass Beads, King - Blush Pink - 150 x 200cm
5.0
Amazon.co.uk

TEDDY FLEECE Weighted Blanket for Adults Kids Soft Sherpa Throw Sleep Therapy Autism Sensory Anxiety Stress Relief Insomnia Sleeping Aid (Silver Grey, Double...
5.0
Amazon.co.uk

Highams Weighted Comfortable Soft Heavy Quilted Pockets Relaxing Blanket, Charcoal Grey 6KG - 125 x 150cm
5.0
Amazon.co.uk