6 week old suddenly sleeping 6-7 hour stretch at night

Question

It has been 3 days since his six week birthday, and our son has suddenly managed to sleep a 6, 6.5 and 7.5 (and counting, as I write this) hour block each respective night.

Update: I picked him up at the 8 hour mark. His eyes were open but he was very docile, he only cried from the cold when I opened his clothes to change his diaper. Based on the sounds from the baby monitor alone, I wouldn't have said he was awake. After feeding, he fell asleep almost immediately after he burped.

Before then, we could manage somewhere between a 3.5 to 4.5 hour stretch once a night.

Since about a week and a half ago, he did stop sleeping long hours during the day, often staying down for a nap less than an hour at a time, except when sleeping while being held.

From what I read, this kind of long night sleeping is attributed to a 6 month old, not a 6 week old.

So far, he has tracked reasonably well for growth and weight, he actually had quite the spurt at around 4 weeks, gaining 400g and 2cm in 9 days, which I am told is a lot by the pediatrician.

I'm just wondering if this is a blessing or a cause for concern. Should I be waking him up?

Answer 1

The age at which a child starts sleeping through the night varies significantly: some start doing it when they are only a few weeks old, whereas the parent "horror stories" tell us about the children who make it through the night for the first time when they were more than a year old!

There is a combination of physiological and psychological factors at play here:

• physiological - a newborn's stomach is simply too small to keep enough food to keep them through the night. As the child (and their stomach) grows it can sleep longer. A rule of thumb is that a baby of more than 5 kilograms is capable of sleeping through the night (physiologically).
• psychological - a newborn is unaware of the difference between the day and the night, and needs time to learn it. Some consider the unconsolable crying in the evenings, that takes place between 4-12 weeks of age, as the first manifestation of the insinctive peur of darkness. This is by no means a generally accepted explanation, but this is again well before 6 months, mentioned in the OP.

Let me also note that the transition from waking every 3 hours to sleeping throughout a night may be indeed a very sharp one.

Finally, note that "6 months" mentioned in the OP is a rather advanced stage - by then the baby acquires lots of other (arguably more complex skills): holding their head, sitting (with a support), turning over in bed, smiling, etc. 6 months is also a time when the diversification of food may have already started. Moreover, at 6 months the child may start again waking at night, e.g., because of teething pains.