There are many reasons an 8 month old wakes at night. Rule out these problems:

1. Does he get enough protein during the day – make sure he has 3 meals, each with 1-2 T of protein such as dairy, meat or egg yolk

2. Make sure he has at least two good day sleeps or he will be overtired

3. Play with him when you get home. No cell phones or interruptions, just focus on him for at least 15 minutes so that he feels comfortable with your lack of presence during the day

4. Make sure he has a doo-doo blanky as this will also help him sleep at night.

Try all of this and if it does not help, get hold of Sleep Sense, my book which will take you through other reasons for night waking.