A good amount of deep sleep for most healthy adults is about 1.5 to 2 hours per night, which typically represents about 15% to 25% of total sleep time. This deep sleep duration aligns with a normal 7 to 8 hours of total sleep and is essential for physical and mental recovery, muscle repair, immune function, and hormone release. Less than 45 minutes of deep sleep is generally considered insufficient for optimal health.

Recommended Deep Sleep Duration

• Adults usually need around 1.5 to 2 hours of deep sleep per night if sleeping 7–8 hours total.
• This corresponds to about 15–25% of total sleep time.
• Deep sleep is a critical phase for full-body restoration and feeling rested.

Importance of Deep Sleep

• Deep sleep supports muscle repair and growth.
• It strengthens the immune system.
• It helps the body release essential hormones.
• Lack of sufficient deep sleep can lead to feeling tired and increased risk of health problems.

Variation and Context

• Amount of deep sleep declines with age.
• Physically active people may require more for recovery.
• The quality of overall sleep, including REM and light sleep, also matters for feeling well-rested.

In summary, aiming for 1.5 to 2 hours of deep sleep within a full night's sleep of 7–8 hours is considered good and healthy for most adults.