Hello and hope you are doing well.
Shuddering or restless in sleep could be due a sleep disorder. These disorders can be like obstructive sleep apnea, wherein during sleep there is an obstruction to airflow due to laxity of the throat muscles during sleep and this could cause restlessness. Hence for therapy CPAP (continuous positive airway pressure) is used to keep it patent. Another cause could be an entity called restless leg syndrome, where there is an odd sensation in the legs during sleep causing the individual to move, which relieves the sensation. These disorders can cause inadequate sleep leading to fatigue and daytime sleepiness. So, I would advise your husband to consult your primary care physician for further evaluation. He may then ask for a sleep study called polysomnography for further evaluation.
Hope this helped and do keep us posted.
I meant I use a bi-pap machine, I saw i put something different after going back and reading... oops but good luck anyways, and my attitude changed from grumpy to happy almost right away, years later I started to have other medical problems but that is a different story ......
Have your husband checked out for sleep disorders, I had a very similar problem and it turned out to be sleep apnea, I could fall asleep no problem, but would wake up all night long, and it seemed like the lightest noise would wake me, the thing was I never really fell into that deep REM sleep, this also caused me to have a bad attitude during the day, on top of being tired all the time.
It turned out I had a severe sleep disorder (sleep apnea) and have to use a b-bap machine (although less severe cases use a c-pap). It was hard to get used to, but when I started to use it, right away I was able to sleep through the night, the machine also makes a noise that drowns out any background noise, so things do not wake me up as easy.
I hope this helps you, a simple sleep study would find if indeed this is the problem. good luck