I want to fall asleep - July Night Edition

Late at night, I stare at my smartphone, rubbing my eyes and leaning against the wall.

I'm so sleepy. I don't want to get up. I recall the painful moment of morning and try to recreate that drowsiness...

But I still can't sleep. What are some tips for falling asleep easily in times like this?

To prevent all of you from starting to search for "how to sleep" like me, I've compiled what I've found.

Why can't I sleep on July nights?

Body temperature needs to drop to fall asleep
→ Drowsiness sets in when core body temperature naturally drops during sleep onset (Reference: van den Heuvel et al., 2005)
In tropical nights, heat easily accumulates in the body
→ In environments with temperatures above 25°C and humidity above 70%, heat dissipation is hindered, making it difficult to fall asleep (Japanese Society of Sleep Research)
High humidity hinders sweat evaporation
→ Sweat dries slowly, and stickiness on the skin surface tends to cause a feeling of wakefulness (Sleep Medicine Reviews, 2018)

To fall asleep, it's important to lower your body temperature.

But in this hot season, this is hindered, which is why we can't sleep.

For wonderful sleep

I've compiled what you can do to fall asleep comfortably, by timing.

July is a hot and humid time. I've also touched on the timing for adjusting air conditioning.

3 hours before sleep

If you're going to do light exercise, do it around this time
→ Warming your body slightly will make your body temperature drop naturally when you go to sleep, making it easier to fall asleep

2 hours before sleep

Best time for a bath (around 15 minutes at 38-40℃)
→ After temporarily raising your body temperature, its subsequent drop aids in smooth sleep onset. Don't forget to rehydrate after bathing.
Start air conditioning/dehumidification
→ Start adjusting the room temperature to 26-28℃ with the air conditioner on gentle cooling or dehumidifier mode.

Before sleep

Incorporate a sleep ritual
→ Dim the lights, quiet the sounds, and lower the room brightness to indirect lighting levels. Take deep breaths to activate the parasympathetic nervous system.

What is a sleep ritual?
It's a habit you perform before bed to make it easier to sleep. It's a routine to relax your mind and body and switch your brain into sleep mode.
While often used for putting children to bed, it's also effective for adults. It helps balance the autonomic nervous system and promotes comfortable sleep.