for nap i use alarm on my phone ,now i set it up for 25 minutes. How is your health ,3 hours of sleep might be effecting you, if it is interrupted sleep in which you hardly get to deep sleep then it is best to target lifestyle to sort it out,diet,exercise ,screentime changes in these factors usually helps ,and if stress is causing you to sleep like this then yogic lifestyle helps and yoga can't be ok without making some changes in diet,exercise ,screentime lifestyle in general ,i am myself dealing with a lot of stress these days but thanks to things i imploy my sleep is still ok.