The first Pokémon Sleep event has been announced and it will begin on Wednesday, August 30th, 2023.

Good Sleep Day Event

The Good Sleep Day event will begin at 4:00 a.m. on Wednesday, August 30! Rest your very best on the night of a full moon! This event will be held once a month for a total of three days: on the day of the full moon and the days before and after it.

During this time period, Drowsy Power will be multiplied by 1.5, and on the day of the full moon (Thursday, August 31), it will be multiplied by 2. Let’s all try to get lots of sleep during the event and research loads of Pokémon sleep styles!

Day 1: Wednesday, August 30, at 4:00 a.m. to Thursday, August 31, at 3:59 a.m.​
Day 2 (the night of the full moon): Thursday, August 31, at 4:00 a.m. to Friday, September 1, at 3:59 a.m.​
Day 3: Friday, September 1, at 4:00 a.m. to Saturday, September 2, at 3:59 a.m.

How to Progress in the Event

Participating in the event is easy! Simply press the “Sleep” button before going to sleep during the event period to track your sleep. A variety of event-related effects will be triggered during your sleep research.

— Night of the full moon (Aug 31) —
Drowsy Power ×2
Pokémon Sleep EXP ×3
Bonus Sleep Points +1000

— Other days (Aug 30, Sep 1) —
Drowsy Power ×1.5
Pokémon Sleep EXP ×2
Bonus Sleep Points +500

Notes about Good Sleep Day

• [Important] Each day of the Good Sleep Day event rolls over at 4:00 a.m.
• Event bonuses apply only to sleep data tracked within the event period.
• If you wait to report sleep data tracked before the event begins, and select “Review Later” during the event, event bonuses will not be applied.
• If you wait to report sleep data tracked during the event, and select “Review Later” after the event has ended, event bonuses will be applied.
• You can only receive bonus sleep points once per day. You will not receive bonus sleep points for the second sleep session in a day.
• Event bonuses do not apply to sleep tracking during the tutorial.
• Event bonuses will be triggered regardless of which site you conduct your sleep research in.

Source: https://www.pokemonsleep.net/en/news/2485/