my bb also has similar problem. he's now 6mth old. i give one more oz of milk to him for his last meal. he still keeps waking up at 4:00am.
After drinking some water, bb sleeps for a while but wakes up again at 5:00am. so annoying.
If that is the case and glad that you know what's keep your bb awake. You should put mosquito repellent or turn on the air conditioner while he is sleeping. As the weather is getting hotter recently...