Hi, I've been taking Jarrow methylcobalamin sub lingual 5000 mcg once a day for the past 6 weeks. Within a week I started to notice an improvement in my symptoms (memory, coordination and breathlessness). I was also sleeping much better. More recently I started to notice my insomnia returning and doubled my B12 intake to 2 x 5000 mcg per day and my sleep quality improved. I've been on the higher dose for about a week now but getting quite a few palpitations on and off throughout the day. Could it be the methylcobalamin perhaps?