[Python] How to Sleep in Python

[Python] How to Sleep in Python

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When you want to pause or delay program execution in Python, you can use the sleep function from the time module. In this post, we will learn various ways to use sleep in Python.

Basic Usage

To use sleep in Python, import the time module and call the time.sleep() function.

import time

print("Start")
time.sleep(2)  # Wait 2 seconds
print("After 2 seconds")

time.sleep() takes a number in seconds as an argument. In the example above, 2 waits for 2 seconds.

Various Time Units

Python’s time.sleep() only supports seconds, but you can convert other time units through calculation:

import time

print("Start")

# Milliseconds (0.5 seconds = 500 milliseconds)
time.sleep(0.5)
print("After 500 milliseconds")

# Seconds
time.sleep(2)
print("After 2 seconds")

# Minutes (60 seconds = 1 minute)
time.sleep(60)
print("After 1 minute")

# Hours (3600 seconds = 1 hour)
time.sleep(3600)
print("After 1 hour")

Time Unit Conversion

Unit	Conversion to Seconds	Example
Milliseconds	1ms = 0.001s	time.sleep(0.5) (500ms)
Seconds	1s = 1s	time.sleep(2) (2s)
Minutes	1m = 60s	time.sleep(60) (1m)
Hours	1h = 3600s	time.sleep(3600) (1h)

Practical Examples

1. Waiting Between Repeated Tasks

import time

for i in range(1, 6):
    print(f"Executing task {i}...")
    time.sleep(1)  # Wait 1 second

print("All tasks completed")

2. Delaying Between API Calls

import time

def call_api():
    print("Calling API...")
    # API call logic

for i in range(3):
    call_api()
    # Wait 2 seconds between API calls (Rate limiting)
    time.sleep(2)

3. Using with Threads

import time
import threading

def worker(worker_id):
    for i in range(3):
        print(f"Worker {worker_id}: Task {i}")
        time.sleep(1)

# Run multiple threads
thread1 = threading.Thread(target=worker, args=(1,))
thread2 = threading.Thread(target=worker, args=(2,))

thread1.start()
thread2.start()

# Wait so main thread doesn't exit
thread1.join()
thread2.join()
print("All tasks completed")

4. Using with Asynchronous Programming (asyncio)

import asyncio

async def main():
    print("Start")
    await asyncio.sleep(2)  # Asynchronous sleep
    print("After 2 seconds")

# Python 3.7+
asyncio.run(main())

Important Notes

• time.sleep() blocks the current thread. Other threads continue to run.
• It does not guarantee exact timing. The actual wait time may vary slightly depending on the system scheduler.
• Sleep for very short durations (nanoseconds) may have reduced accuracy.
• In asynchronous programming, you must use asyncio.sleep(). time.sleep() blocks the event loop.

time.sleep() vs asyncio.sleep()

time.sleep() - Synchronous Blocking

import time

print("Start")
time.sleep(2)  # Blocking
print("After 2 seconds")

asyncio.sleep() - Asynchronous Non-blocking

import asyncio

async def main():
    print("Start")
    await asyncio.sleep(2)  # Non-blocking
    print("After 2 seconds")

asyncio.run(main())

In asynchronous programming, using asyncio.sleep() allows other coroutines to run, making it more efficient.

Practical Tips

1. Sleep in Milliseconds

import time

# Wait 500 milliseconds
time.sleep(0.5)

2. Dynamic Sleep Using Variables

import time

delay = 2.5  # In seconds
time.sleep(delay)

3. Random Delay (Rate Limiting)

import time
import random

# Wait for a random time between 1 and 3 seconds
delay = random.uniform(1, 3)
time.sleep(delay)

I hope this post helps you understand how to use sleep in Python!