Hello and thank you for your question. The weakness in the legs may be more a factor of deconditioning which is a major factor in patients with dementia. Patients with dementia often have problems with sleep and also have problems with maintaining a good diet. This leads them to have wasting of muscle in their body and causing them to have the weakness. Patients with dementia also suffer from depression and it is possible that your husband's sleeping during the day may be related to this depression.