you are there. If the cry does not sound urgent, then just listen. If the crying stops after a minute or two, he can be left. If not, he may just need to hear your voice, sense your smell and feel your touch on his body, but without picking him up. A bit of humming or singing is often all that is needed for him to forget his subconscious concerns and drift off again. If your simple presence by sound and smell is not enough, he may just need a cuddle and a quiet sit. If he is more agitated, it may require a full change and feed to relax him back to sleep. My main message is, try the little things first. Don't immediately pick him up, fully wake him up or feed any cry which you cannot understand. Immediate attention, in the form of listening and just being there is far better than leaving him to cry more and more vigorously until you have a fully awake baby and a full-blown 1 - 2 hour catastrophe on your hands!
   If a baby has recently grown out of night feeds, and he starts waking up again in the night (a most common situation which really deflates the elated mother), always try the above methods before considering re-introducing night feeds. If the crying persists it may have some organic cause such as illness, or being too hot or cold. If insects and mosquitos are abundant in your area, even with screens on the window, set up a mozzie net over your baby.
   Most children have unsettled periods of night sleep up until about the age of 4 or 5. After that time they are more able to flow in and out of the different levels of consciousness without needing the comfort of a parent. Over the years, all of my kids have had, and still have, different sleeping patterns. Some examples here will help to show the variations which can occur even in families where (my own) sleep time routines have been consistent and yet they each have their own mental conditions to deal with.
   As a baby, my eldest son was always a very settled sleeper who wasn't fond of being cuddled or cajoled to sleep. Still, at age 13, he never has any trouble getting to sleep and never wakes in the night.
   My second son is on occasions a sleep talker, a sleep walker, and always wakes up in a totally disorganised bed from rolling around.  As a baby, and until about 3, he often woke in the night, when just a reassuring word from me and a re-tuck of the blankets would get him back to sleep again. I eventually broke his habitual waking (that I believed was caused by underlying insecurity) by moving in to sleep in the same room as him for several months when he was 3. As soon as he woke, I was close enough to reassure him with my voice that it was OK and he 

then quickly dropped back to sleep. This arrangement also saved me the disturbance of getting out of bed and walking down the hall to his room.
   My eldest girl, was a very settled sleeper as a baby who rarely wakes at night and always sleeps very deeply.
   My second daughter (finally! - at the age of 5) is now sleeping most nights all the way through. As a baby she was sometimes difficult to settle and often just woke for reassurance in the night. She is such a light sleeper that she used to wake regularly until the age of 3 because she couldn't find her teddy, her pillow was on the floor, or because she needed to go to the toilet. In trying to avoid such situations I had to always make sure she was firmly tucked in, not likely to lose anything in the night, and limit all drinks from about 4 pm so that her bladder was empty by bedtime. As she has grown older, she has learned to tend to her own needs in the night, but she still occasionally wanders to my bed or calls for me to turn on the light on dark nights. At one time, when my children and I were sleeping all together in a large room, merely the sound of my voice was enough to settle her again. She is always the first one up at the earliest sound of activity in the mornings and can occasionally be heard singing to herself an hour after going to bed at night.
   For the first 2 years of her life, my youngest girl invariably slept flat on her back but with her hands up by her ears, exposed from the bedding! For her first two winters I had a problem with her waking up every night due to very cold hands, sometimes quite swollen. I tried tucking her hands down (they'd come up again). I tried mittens (she hated them). I tried warming the room more (but that made it stuffy). I tried sleeping her in with me (but she still poked her hands up and I'd spend most of the night trying to rearrange the bedding). I tried an electric blanket (but that made no difference to her exposed hands). In the end I had to move her to a bedroom closer to the main fireplace, keep it lit all night and leave the door open as well as checking on her often throughout the night. I also had to be patient, attend to her needs as they arose and wait for the cold months to pass. By the age of 3 she was able to learn to snuggle up under the blankets and that winter she slept fine. But she still prefers to sleep flat on her back with her hands almost on her head! Weird.
   The point of these stories is that each child can be radically different in their sleeping idiosyncrasies, and that for each one you may need to find different creative strategies to help them (and you) get the best night's sleep. It's a challenge for sure.