Can Lexapro (escitalopram) still cause sleepiness in low doses, say 10mg per day this is treatment for ocd?

Some people. Yes in some people - try taking the medication at bedtime if you feels like it makes you sleepy.
Yes. Lexapro (escitalopram) is usually more sedating than not even in lower doses. I usually recommend that it be taken at dinner time or even bedtime not during the day to minimize the sedating side effects.