In my experience, if you can get him to have a good couple of day sleeps - four or more hours during the day, the night sleeps will sort themselves out. Sorting out the day sleeps, however, is a challenge.

When do you bath Lachlan? Perhaps you could try bathing him before his morning sleep. If you could BF him before a bath, then bath him, he might be relaxed enough to get over the "sleep hump". Perhaps some baby massage might help relax him as well.

What kind of environment is he sleeping in? While I'm sure you realise this, a fairly quiet darkened room is probably the best environment for a baby to get a decent, uninterrupted sleep in (you'd be surprised how many parents I deal with who don't realise that fact, and this it is unreasonable that their baby has trouble sleeping in a brightly-lit room with a television blaring in the background). Are there lots of visitors, or activities going on at home? Or dioes he spend lots of time out and about on the move? If so, it might be helpful to reign things in for a week or two - get your partner or a friend to go out and do the shopping, put a ban on visitors, and focus on creating a calm and quiet environment until sleep problems sort themselves out.

What is the timing of his BF? Is he falling asleep on the breast? I know we had trouble with our first when she was falling asleep on the breast - some baby sleep experts believe that babies who fall asleep on the breast are less able to settle themselves during wakeful periods because the environment they wake up in (alone on the cot) is different from the one they went to sleep in (cuddled to the breast). However, BFing to sleep Is a cute way to go, and I know my wife was quite sad to give it up. Our little one's sleep did improve afterwards, though.

Another option to consider is enlisting an ally. Find a friend or family member who doesn't get flustered at the sound of a baby crying and get them in to help out. BF Lachlan, change his nappy, rug him up warm and wrap him up tightly, and let your friend/family member cuddle him quietly in a darkened room. Then, get some well-earned rest yourself. Sometimes babies key into the stress of the person comforting them, and lets face it, who doesn't get stressed when their baby is crying?

Like the others, I don't think that formula is the answer to this problem - formula is known to create tummy-aches and generally cause more trouble than it solves. BF for a baby that has been exclusively BF until now will provide both a full tummy and emotional comfort that bottle-feeding does not.

Over-tiredness is a horrible vicious cycle that is extremely hard to break - the more over-tired the bub gets, the less able he is to settle himself, and the more times he spends awake. A final option, as suggested by others on this thread, would be to contact Karitane, Tresillian, or one of the private baby clinics scattered around, and arrange for an in-home assessment or to travel there and room in, where staff can be on hand to provide physical support.

As you pointed out, a baby this age should be getting around fifteen hours a day of sleep. I find it's best to be guided by the baby, though, than to count the clock - if he is settled and happy and sleeping well on twelve hours of sleep, then that is probably enough; if, on the other hand, he is grizzly, maybe he wants an extra hour or two. Of course, the trick is to work your way up from the 4+ hours of sleep he is getting at the moment.