you can take it at night if you want, but you may have some trouble sleeping if you do. as for the sleepiness during the day: what is your diet look like? in a nutshell, t3 is throwing your metabolism into overdrive. just in thermogenesis alone your energy expenditures will increase even at rest. with that being said, glucose levels will be harder to sustain than normal. don't take this the wrong way: i'm not saying you need to increase carb intake just because you're on t3. i'm saying: what does your current intake look like? knowing that answer can tell us it may be remedied nutritionally.