by The Amerisleep AS4 is designed for side sleepers -- specifically those who need more pressure relief than the popular AS3 provides. Here's our full review of the medium-soft model.
Amerisleep AS4: Quick Verdict
Best for: Side sleepers, lightweight sleepers under 150 lbs, pressure relief
Firmness: Medium-Soft (4/10)
Price (Queen): $1,399
Trial: 100 nights | Warranty: 20 years
AS4 Construction
- 3" Bio-Pur foam (top): One inch thicker than AS2/AS3's comfort layer, allowing deeper shoulder and hip contouring.
- 2" HIVE transition layer: Zoned support -- softer under shoulders and hips, firmer under lumbar.
- 6" Bio-Core base: Durability foundation backing the 20-year warranty.
AS3 vs AS4 vs AS5: Which Side Sleeper Model?
| Model | Firmness | Side Sleeping | Price (Queen) |
|---|---|---|---|
| AS3 | Medium (5/10) | Good for average-weight side sleepers | $1,299 |
| AS4 | Medium-Soft (4/10) | Best for most dedicated side sleepers | $1,399 |
| AS5 | Soft (3/10) | Best for lightweight / strict side sleepers | $1,499 |
Final Verdict
The Amerisleep AS4 is the sweet spot for dedicated side sleepers -- softer than the AS3 but not the extreme softness of the AS5. The 20-year warranty makes it a strong long-term investment.
Plant-Based Foam Alternative
Amerisleep AS3 — From $1,049 Queen
Bio-Pur plant-based foam, 100-night trial, 20-year warranty. Universal medium-firm feel.
Frequently Asked Questions
Is the Amerisleep AS4 too soft?
The AS4 is medium-soft (4/10), appropriate for side sleepers but too soft for stomach sleepers and most back sleepers. If you're not primarily a side sleeper, the AS3 is likely a better fit.
Who should choose the AS4 over the AS3?
Choose AS4 if you primarily sleep on your side and weigh under 200 lbs, especially if you experience shoulder or hip pain on your current mattress. Choose AS3 if you switch positions frequently or share the bed with a back sleeper.