Hi
Older dogs can certainly develop forms of senility or dementia. Their sleep patterns can change (they forget its the middle of the night) and they can be restless and active during the night because they are confused. Its not helped if there are also cataracts affecting vision or any hearing loss. Presumably his hypothyroidism is controlled by his medication and you go for regular checks? I think this one is for your vet to work out and maybe some supplements or further medication can be prescribed to help.
Cathy Wickenden BVet Med MRCVS
Barton Lodge Veterinary Centre
1 Midland Road, Hemel Hempstead, Hertfordshire, HP2 5BH
Tel: 01442 216048 24 hours
[
www.bartonlodgevets.co.uk]