Summer brings longer days and warmer weather, but for many families it also brings more disrupted baby sleep. Parents often notice shorter naps, more night waking, and unsettled bedtimes during hot or humid weather, and wonder what they can do to help.

At Restful Sleepers, this is one of the most common seasonal concerns I hear from families. The good news is that with a few thoughtful adjustments to your baby’s sleep environment, you can support safer, more comfortable sleep during summer.

Why Heat and Humidity Affect Baby Sleep

Babies aren’t able to regulate their body temperature as efficiently as adults. When they’re too warm, their bodies stay more alert, making it harder to fall asleep and stay asleep. Humidity can add another layer of discomfort by stopping sweat from evaporating properly.

This often shows up as:

• Frequent night waking
• False starts after bedtime
• Shorter or unsettled naps
• Difficulty settling, even with a familiar routine

These changes are common in summer and don’t mean your baby’s sleep has suddenly “gone backwards.”

What Is the Ideal Room Temperature for Baby Sleep?

The recommended room temperature for babies is 18–22°C. This range supports deeper, safer sleep and reduces the risk of overheating. In reality, many homes, especially during New Zealand summers, regularly sit above this range. If the room feels uncomfortably warm to you, it’s likely too warm for your baby as well. A simple room thermometer can be helpful, but your baby’s comfort matters just as much as the number.

Signs Your Baby May Be Too Hot

Rather than checking hands or feet (which are often cool), feel your baby’s chest or back. Signs they may be too warm include:

• Sweaty neck, chest, or back
• Damp hair
• Flushed skin
• Increased restlessness or waking

If you notice these signs, adjusting clothing or airflow can help.

Creating a Cooler, More Supportive Sleep Environment

At Restful Sleepers, I often remind families that sleep is influenced by environment as much as routine. During summer, small changes can make a big difference.

• Keep the Room Dark: Darkness supports melatonin and helps babies settle, even when daylight stretches later into the evening. Blackout curtains can also reduce heat build-up during the day.
• Improve Air Movement: Air circulation helps rooms feel cooler, some ideas to do this include: use a fan to circulate air (not blowing directly on your baby), open windows early morning or evening when temperatures drop, and close curtains and windows during the hottest part of the day.
• Cool the Room Before Bed: If possible: ventilate the room before bedtime, use fans or air conditioning gently and avoid sudden temperature changes overnight. If you are using air conditioning ensure it is cooling gently and consistently. 
• Even in summer, safe sleep guidelines stay the same: baby on their back, a firm and flat mattress and a clear sleep space.

What Should Baby Wear to Sleep in Summer?

Overdressing is one of the most common issues I see during warmer months. Choose: lightweight layers, natural fibres like cotton or merino, which regulate temperature and wick moisture (merino is suitable year-round and can actually help keep babies cool in summer), and short-sleeved bodysuits or singlets on very warm nights. For sleep sacks you can choose a low TOG (0.2–0.5) or possibly go without on very hot nights, if safe to do so

Always dress your baby for the room temperature, not the season.

The Takeaway for Parents

If your baby’s sleep feels harder in summer, you’re not alone. Heat and humidity can disrupt even well-established sleep patterns. By focusing on:

•  A cooler sleep environment
• Breathable clothing and bedding
• Air movement and darkness
• Gentle, responsive support

…you can help your baby stay more comfortable and support better rest for the whole family.

And remember, seasonal sleep disruptions are temporary. If you’re feeling unsure how to adapt your baby’s sleep during summer, personalised guidance, like the support offered through Restful Sleepers, can help you make small, practical changes with confidence.