Sleep Calculator
Optimal Bedtime & Wake-up Time Based on Sleep Cycles
Calculate the best times to sleep or wake up based on 90-minute sleep cycles. Plan your sleep scientifically for refreshed mornings.
😴 What are Sleep Cycles?
A sleep cycle lasts approximately 90 minutes and includes 3 stages of NREM sleep and REM sleep. Waking up at the end of a cycle minimizes sleep inertia (grogginess). Completing 4-6 cycles (6-9 hours) per night is ideal for most adults.
(includes 15 min to fall asleep)
📊 Recommended Sleep by Age
| Age Group | Recommended | Acceptable Range |
|---|---|---|
| Newborn (0-3 mo) | 14-17 hours | 11-19 hours |
| Infant (4-11 mo) | 12-15 hours | 10-18 hours |
| Toddler (1-2 yr) | 11-14 hours | 9-16 hours |
| Preschool (3-5 yr) | 10-13 hours | 8-14 hours |
| School Age (6-13 yr) | 9-11 hours | 7-12 hours |
| Teen (14-17 yr) | 8-10 hours | 7-11 hours |
| Adult (18-64 yr) | 7-9 hours | 6-11 hours |
| Senior (65+ yr) | 7-8 hours | 5-9 hours |
📝 How to Use
- Choose a mode: Wake-up time or Bedtime
- "Wake-up mode": Set when you want to wake up to get ideal bedtimes
- "Bedtime mode": Set when you go to bed to get ideal wake-up times
- 15 minutes to fall asleep is automatically included
- Prioritize 5-6 cycle options (7.5-9 hours)
💡 Tips for Better Sleep
- Go to bed and wake up at the same time every day
- Avoid blue light (phone, PC) 1 hour before bed
- Keep bedroom temperature at 65-68F (18-20C)
- No caffeine within 6 hours of bedtime
- Limit naps to 20 minutes or less
❓ FAQ
Sleep follows a ~90-minute cycle from light sleep to deep sleep to REM sleep. Waking at the end of a cycle minimizes sleep inertia (that groggy feeling).
On average, a healthy adult takes about 10-20 minutes to fall asleep. 15 minutes is the commonly accepted average.
Trying to repay sleep debt all at once has limited benefits. A consistent sleep schedule is much healthier for your body and mind.
📚 各地区计算规则说明
计算逻辑
采用公开的金融、贷款、比率与单位换算标准公式。
参考范围
参考公开标准与各地区常见实务规则。
前提条件
税费、费率、上限会因地区和机构而不同。
结果解读
结果可作为基准情景。正式决策前请与当地机构报价和税务规则对比。
地区默认值
货币: CNY
单位: metric
税务模型: US payroll estimate
法规提示
本工具基于地区预设进行估算。实际合同条款与法定上限可能因机构和当地法规而不同。
建议操作
- 正式申请前请至少比较 2~3 家本地机构方案。
- 再次核对费用、税务处理和提前还款条款。
- 用利率 +1~2% 与收入下降场景再测一次。
做真实决策前，请先确认当地机构的最新条款。