How Babies Sleep

1. Light exposure profoundly impacts baby's sleep patterns

Not all light is the same. Three aspects of the light you are exposed to are crucial for photoentrainment, or for setting the phase of your rhythm: Time of day of light exposure, Light intensity, Light wavelength or color.

Light regulates circadian rhythm. Our bodies have an internal clock that is primarily influenced by light exposure. This clock, located in the suprachiasmatic nucleus (SCN) of the brain, controls the release of sleep-related hormones like melatonin.

Blue light suppresses sleep. Morning sunlight, rich in blue wavelengths, signals the body to wake up and be alert. Conversely, evening light with less blue content promotes sleepiness. Artificial lights, especially screens, often contain high levels of blue light, which can disrupt natural sleep patterns.

Timing matters. Light exposure at different times of day can either advance or delay the sleep cycle:

• Morning light: Advances sleep cycle (helps with earlier bedtimes)
• Evening light: Delays sleep cycle (makes it harder to fall asleep early)

2. Establish consistent Day and Night Modes for optimal sleep

To get the clock well entrained, we have to present it with zeitgebers. The main zeitgeber is light, but does any light reset the clock? The answer is no.

Create distinct environments. Establishing clear differences between daytime and nighttime environments helps reinforce a baby's natural sleep-wake cycle.

Day Mode:

• Expose baby to natural daylight
• Maintain normal household noise levels
• Engage in stimulating activities

Night Mode:

• Use only red light
• Minimize noise and stimulation
• Maintain a consistent bedtime routine

Consistency is key. Repeating these patterns daily strengthens the baby's circadian rhythm, making it easier for them to fall asleep and stay asleep through the night.

3. Red light promotes melatonin production and better sleep

When you put the baby down to sleep, turn only the red light on. This way, in Night Mode, the baby's clock won't be reset to morning time and melatonin production will not be suppressed—in other words, your baby will sleep.

Red light doesn't disrupt melatonin. Unlike blue and white light, red light has minimal impact on melatonin production, the hormone crucial for sleep.

Applications of red light:

• Use during nighttime feedings and diaper changes
• Install in nursery for bedtime routines
• Employ as a nightlight for older children

Transition to red light. Begin using red light 30-60 minutes before bedtime to signal the body that it's time to sleep. This can help babies fall asleep faster and stay asleep longer.

4. Create an ideal sleep environment with blackout shades and white noise

Get blackout shades (see "Helpful Baby Items" on page 193) that will completely block out the light. Get them for baby's sleep area, whether it is a nursery or your bedroom, as well as for the diaper changing area, if that is in a different room.

Dark room promotes longer sleep. Blackout shades prevent early morning light from disrupting sleep, especially important in summer months when sunrise can be very early.

White noise masks disturbances. A consistent background sound can help drown out household noises or outside disturbances that might wake the baby.

Key elements of an ideal sleep environment:

• Complete darkness (use blackout shades)
• Comfortable temperature (68-72°F / 20-22°C)
• White noise machine or app
• Comfortable sleep surface (firm mattress for safety)

5. Implement a structured sleep and feeding schedule

By establishing feeding and sleeping routines, you and your baby will both learn to understand what the baby needs at certain times. You and the baby will learn that he is upset just before nap time because he is tired, and that going to sleep will make him feel better.

Predictability reduces stress. A consistent schedule helps both baby and parents anticipate needs, reducing fussiness and confusion.

Gradual implementation. Start by setting consistent wake-up and bedtimes, then gradually add in scheduled feeding times and naps.

Sample schedule for a 6-month-old:

• 7:00 AM: Wake up and feed
• 9:30 AM - 11:00 AM: Morning nap
• 11:00 AM: Feed
• 2:00 PM - 3:30 PM: Afternoon nap
• 3:30 PM: Feed
• 6:30 PM: Dinner/last feed
• 7:00 PM: Bedtime routine
• 7:30 PM: Bedtime

6. Limit daytime naps to encourage longer nighttime sleep

Babies who sleep more during the day go to bed later at night and sleep less during the night. It's really logical, and what it means for your baby is that you might have to restrict daytime napping.

Balance daytime and nighttime sleep. Babies have a total daily sleep need that decreases as they age. Excessive daytime sleep can lead to shorter nighttime sleep.

Gradually reduce naps. As babies grow, they require fewer and shorter naps. Follow age-appropriate guidelines:

• Newborns: 4-5 naps per day
• 3-6 months: 3 naps per day
• 6-12 months: 2 naps per day
• 12-18 months: 1-2 naps per day
• 18 months-3 years: 1 nap per day

Wake a sleeping baby. It's okay to gently wake a baby from a nap if they've slept longer than recommended for their age. This helps maintain the overall sleep schedule and ensures they're tired enough for nighttime sleep.

7. Use Gentle Sleep Training to teach self-soothing

Here is my simple four-step program: Step 1. Adjust naps as necessary. Step 2. Follow your bedtime routine and timing. Step 3. Make a pact with yourself and make a plan. Step 4. Let your baby cry for at least ninety seconds.

Self-soothing is crucial. Teaching babies to fall asleep independently is key to longer sleep stretches and fewer night wakings.

Gentle Sleep Training steps:

1. Ensure baby is ready (typically around 3-4 months old)
2. Create a consistent bedtime routine
3. Put baby down drowsy but awake
4. If baby cries, wait 90 seconds before responding
5. Comfort briefly without picking up baby
6. Repeat as necessary, gradually increasing wait times

Consistency is key. Stick to the plan for at least a week to see improvements. Be prepared for some challenging nights as baby learns new sleep habits.

8. Understand and manage sleep regressions

We learned in step 2 that babies' total sleep continuously decreases from birth, when they sleep, well, most of the time, to adulthood, when it's just around eight hours a night.

Sleep needs change. As babies grow, their sleep patterns evolve, sometimes leading to temporary disruptions known as sleep regressions.

Common sleep regression periods:

• 4 months: Major sleep cycle changes
• 8-10 months: Increased mobility and separation anxiety
• 12 months: Nap transitions and increased independence
• 18 months: Language explosion and testing boundaries
• 2 years: Imagination development and nighttime fears

Maintain routines. During regressions, stick to established sleep routines as much as possible. Adjust nap times and durations if necessary, but avoid creating new sleep associations that may be hard to break later.

9. Adapt sleep routines for travel and time zone changes

Based on what we know today about the circadian clock and jet lag, I developed a method to avoid or at least minimize the discomfort associated with crossing time zones.

Gradual adjustment. When traveling across time zones, gradually shift your baby's schedule before and after the trip to minimize disruption.

Tips for managing jet lag:

• Shift bedtime by 1 hour every 1-2 days before travel
• Use blackout shades and red light to maintain sleep environment
• Expose baby to sunlight during wake hours in the new time zone
• Be patient – it may take up to a week for full adjustment

Maintain sleep cues. Bring familiar sleep items (like a favorite blanket or white noise machine) to help recreate the home sleep environment while traveling.

10. Recognize signs of sleep readiness in babies

When baby is about three to four months old or weighs eleven pounds and sometimes sleeps longer stretches (six hours or more) at night, you can start sleep training.

Physical readiness. Babies typically become physically capable of sleeping longer stretches when they reach about 11 pounds (5 kg).

Signs of sleep readiness:

• Weighs more than 11 pounds
• Can sleep 5-6 hour stretches occasionally
• Doesn't seem very hungry during night feedings
• Shows increased daytime alertness

Behavioral cues. Look for signs of tiredness such as rubbing eyes, yawning, or becoming fussy. Putting a baby to sleep when they first show these signs can prevent overtiredness and make falling asleep easier.

Last updated: April 16, 2025