A couple ideas from what you said and what we experienced... Our first had jaundice (had it worse than it appeared by skin color). He was VERY sleepy all the time because of the jaundice and then because of being sleepy, he didn't eat much and then lost "too much" weight because of it. He still had wet and poopy diapers, but just didn't eat ENOUGH. He'd literally just eat and sleep and not be able to stay awake through a feeding. He was borderline for having the billiblanket...we first sunned him in the window all the time to see if that would work to help the jaundice and thankfully it did. I think jaundice usually peaks at 5 or 6 days though. May be worth a doctor visit to ease your mind if it really doesn't seem right...to make sure he's gaining weight alright and all.
Another thought is if he's awake and alert just fine at other times is to get him going with a routine/schedule. This is yet another thing that a routine/schedule helps with...being alert to eat. The routine is eat, then awake play time, then sleep, then eat, then awake play time, then sleep, and so on. When you nurse, a hormone is released for both you and the baby that make you sleepy (same hormone as in turkey that makes you sleepy). So the routine helps because he is then eating right after he just napped (except the bedtime feeding), but you may need to still get him out of the drowsy state just after eating. So a routine helps to:
- have alert feedings because the baby is not sleepy/ready for a nap when trying to eat
- helps the baby to distinguish day from night and thus helping the baby to sleep through the night from the time he/she is about 13 pounds or 2-3 months old, which is good for restful sleep for baby, as well as the rest of the house...with the routine, the baby will typically start sleeping through the night around this time on their own
- helps to promote full feedings so sleep is not interupted due to hunger (so it then promotes full naps because of the full feedings)
- helps to promote full naps as opposed to cat naps, which allows for more restful sleep as a full nap allows the baby time to reach REM sleep
- helps the parent to know what the child needs, like especially providing the opportunity to nap before the baby is OVERtired because often when they show signs of being tired, they are really overtired and then have trouble falling asleep due to being overtired.
When doing the routine/schedule, after feedings it may be necessary to play with him and stimulate him right after a feeding until he comes out of the drowsiness from that hormone being released. I did that with my kids and then they'd be alert until I laid them down for nap at nap time...then they'd fall asleep on their own at nap time.
So a schedule would look like this....a 3 hour schedule which we continued up until after the baby was sleeping through the night and then showed signs of being ready to extend to a 4 hour schedule (signs being we had to wake them for feedings routinely after being established in the routine that they would wake on their own for the feeding at the right time and also seeming like they could go longer between feedings since they were less focused while eating anymore). So the schedule looked like this until I want to say about 4 months...
6am eat
7:30-9am nap
9am eat
10:30-12noon nap
12 noon eat
1:30-3pm nap
3pm eat
4:30-6pm nap
6pm eat
7:30-9pm nap
9pm eat
10:30eat and to bed for the night
Before sleeping through the night, I'd feed on demand in the middle of the night and then wake the baby to eat in the morning at 6am to begin the schedule of the day.