1. Your baby's physiological drive to sleep is less.

As night falls, your baby's melatonin levels increase while cortisol decreases. Melatonin is the hormone that induces physiological sleepiness, and its production is regulated by the brain in response to light and dark cycles. The highest levels of melatonin are typically reached at midnight, while they decrease by 6 am. This natural surge in melatonin production overnight is why it's much easier to sleep at night than during the day. In contrast, cortisol levels drop at night, reaching their lowest point around midnight, and peak at around 8 am to help wake us up and keep us alert throughout the day. Therefore, napping during the day can be challenging due to the lower levels of melatonin and higher levels of cortisol.

2. You miss their sleep window.

Infants experience biological sleep windows that align with their circadian rhythms, as well as physical sleep windows when they feel tired but not overly fatigued. Missing these windows can be detrimental to your baby's sleep quality, much like a surfer missing the right wave. As your baby grows, the sleep window shifts from 60 minutes after waking up as a newborn to 2-3 hours after waking up at 8 or 9 months old. Keeping track of these changes can be challenging, but it's important for promoting healthy sleep habits.

3. They are ready to drop a nap.

It's important to know that as a newborn, your baby will require 3-5 naps throughout the day. However, as they grow, they will only need one nap when they reach 18 months old and will eventually stop needing naps completely by the time they turn 3 years old. 

If you're struggling with your baby's naps, it could be a sign that their routine is not aligned with their sleep needs. Here are some classic indicators that your baby's routine is off: 

A. Your baby may play in their cot for a long time before falling asleep. 
B. They may have short naps throughout the day. 
C. They may suddenly cry excessively during nap or bedtime. 
D. Your baby may start waking up frequently at night, especially before 10pm. 
E. They may start waking up earlier than 6:30am. 
F. Your baby may become increasingly irritable between naps. 
G. They may fall asleep as soon as you start driving anywhere. 

Remember, your baby's sleep routine will change over time, so it's important to adjust your expectations and routine accordingly.

4. It’s after 3pm.

It can be quite challenging to catch some shut-eye after 3 o'clock without a little assistance. This is a common occurrence, and instead of attempting to sleep train during the late afternoon, it's advisable to adjust your expectations. Dr. Richard Ferber refers to the hours between 3pm and 7pm as the "non-sleep zone," and many mothers know that it's an ideal time to indulge in some chocolate cake and coffee. As the day wears on, we all tend to feel more fatigued and irritable, but due to the intricacies of the circadian rhythm, it's not the best time to anticipate lengthy naps. Your child will likely only snooze for 30-45 minutes during this period and may require some rocking or a stroll in the stroller. Fortunately, this nap after 3pm generally disappears around 7-8 months, and this is a completely normal occurrence.

5. Your babies sleep environment is no good.

It's hard to make babies sleep during the day, and sometimes their routine can be disrupted. If you want your baby to sleep well, you need to create the perfect sleep environment. If your baby struggles to nap in their room with the curtains open and loud noises from the TV in the lounge, you should make some changes. Start by closing the curtains, making the room dark, and using some soothing white noise. By doing this, you are creating a peaceful and comfortable sleep environment that will help your baby nap better. Don't worry, you are not creating a problem for yourself, you are creating the best sleep environment for your little one. When your baby is over-tired, and you need to rock them to sleep, you will have a better chance of a nap happening, and your night's sleep will not be disturbed.