Could someone please explain to me why the first sentence below uses the word 'blanket' in singular form whilst the second sentence uses plural? I know how to change them to use one or the other but I am at a loss to understand the why this is so.
They were also 20 times more likely to completely clear their insomnia compared to those using a light blanket. Those who used weighted blankets also had reduced symptoms of fatigue, depression and anxiety during the day.