Split Nights

Split nights, biphasic, bimodal, diphasic, segmented, or divided sleep. This is when your baby or toddler is awake and ready to party for several hours in the middle of the night. Whatever you want to call it, there’s one thing for certain: it’s not fun!

Young babies have what is called a polyphasic sleep pattern, as their sleep is segmented into multiple naps across the day, usually followed by a long sleep overnight (which might include a couple of quick feeds).

By about 13-18 months old, they will shift into a biphasic sleep pattern where their sleep is split into only two segments: one nap followed by their 10-12 hours of sleep overnight.

Once your child is about 2.5-3.5 years old, they will be ready to move into a monophasic sleep pattern where, like us, they only have one long sleep in a 24-hour period, usually occurring during nighttime hours.

Most adults are monophasic sleepers, although biphasic or polyphasic sleep does occur naturally in some people. Others may actively pursue this pattern of sleep as they believe it makes them more productive, such as the Spanish tradition of the afternoon “siesta,” where an afternoon nap is taken to avoid working through the hottest part of the day.

It’s thought that the custom of sleeping for one long stretch overnight may have been shaped by the modern industrial workday. Before the introduction of artificial light, our ancestors would have gone to bed at sundown, slept for several hours, then woken for a period of time before going back to sleep again until sunrise.

So, when your baby or toddler wakes for a midnight party session, rest assured, there’s nothing “wrong” with them. However, it can become problematic when their sleeping pattern doesn’t necessarily match up with yours.

The good news is, we can usually fix this.

If you have a young baby or toddler who is still napping during the day and their night sleep is broken with extended wakeful periods, it might be time to reduce or drop a nap, or adjust their bedtime. Our ability to fall asleep and stay asleep is driven by our circadian rhythm and our homeostatic sleep drive. If your child sleeps for too long during the day, they won’t have the opportunity to build up enough sleep pressure to sleep solidly at night.

(Bonus tip: Too much stimulation during a night wake can also impede your little one's ability to resettle quickly, so avoid turning on the lights, offering food or milk (if not due a feed), or getting them up/taking them out of the room).

I see this pattern of segmented night sleep occur most commonly in 3-4-year-olds who are still napping during the day. Parents come to me with the issue of their child waking in the night and taking hours to go back to sleep. The next day, everyone is exhausted, so they allow their child to have a nap, and the cycle continues.

The solution in this case is usually to drop the nap. Unfortunately, this isn’t always easy. It will likely mean you have a very tired and cranky child on your hands for a few days when you take away their opportunity to catch up on sleep during the day. However, once you break the cycle, they’ll start sleeping solidly at night, waking refreshed and ready to tackle a full day ahead.