Sleep is one of the most mysterious and essential parts of our lives. It’s a state where our awareness of the world fades, our responsiveness to what’s happening around us decreases, and our bodies fall into a rhythm of unique physiological patterns.
On average, sleep takes up one-third of your life, highlighting its importance. Beyond rest, sleep is a dynamic process that: Boosts cognitive performance, Supports emotional regulation, Balances the body’s metabolic state. Understanding these intricacies emphasizes why sleep is a cornerstone of health and productivity
What makes us Sleepy?
- The Circadian Rhythm
- Sleep Pressure from hormones
A signal from your internal 24-hour clock, located deep within the brain, governs your natural sleep-wake cycle. This clock aligns with environmental cues like light and darkness, helping you maintain a consistent schedule.
The longer you stay awake, the more a chemical pressure builds in your brain, making you feel increasingly sleepy. These Chemicals include but not limited to Melatonin hormones, Cotisol hormone and so many others
All sleep is not the same
Not all sleep is the same. Your brain cycles through two main types of sleep: non-Rapid Eye Movement (NREM) sleep and Rapid Eye Movement (REM) sleep
NREM sleep is divided into three stages. Stage 1, also known as N1, marks the transition from wakefulness to sleep and lasts just one to seven minutes. During this phase, the body begins to relax, and brain activity slows, though brief movements and light changes in brain patterns may still occur. Stage 2 (N2) follows, where the body enters a deeper state of relaxation, with a drop in temperature, slower breathing, and reduced heart rate. Brain activity in this stage shows bursts of activity that help block external stimuli, making it harder to wake up. This stage can last 10 to 25 minutes in the first sleep cycle and becomes longer as the night progresses. By the time you reach Stage 3 (N3), also known as deep or delta sleep, muscle tone, pulse, and breathing slow significantly.
After NREM sleep, the brain transitions to REM Sleep , where activity ramps up to levels similar to wakefulness. During REM sleep, the body experiences temporary paralysis, except for the eyes and breathing muscles. This stage is most known for vivid dreams, as the brain becomes highly active. REM sleep is essential for cognitive functions such as memory, learning, and creativity. A typical sleep cycle lasts about 90 minutes, starting with NREM stages and transitioning to REM.
Alarms: Hidden Truth
A phone alarm App
Bed side Alarm
Waking up at the wrong stage of sleep can have a profound impact on how you feel throughout the day. Ideally, you want to wake up during a lighter stage of sleep, when your body and brain are naturally closer to being awake. This makes it easier to feel refreshed and alert. However, being jolted awake during a deeper stage, like REM or deep sleep, can leave you groggy, disoriented, and struggling to fully wake up—a phenomenon sometimes referred to as "sleep inertia." Traditional alarms, whether they’re mechanical bedside clocks or phone alarms, can abruptly disrupt your sleep cycle. These sudden jolts wake you up using the body’s fight-or-flight response, triggering a sharp spike in stress hormones like adrenaline and cortisol. This causes your heart rate and blood pressure to rise rapidly, setting an unhealthy tone for the day. If your alarm wakes you during the restorative deep sleep or REM stage, the consequences can be even worse, as these phases are crucial for physical recovery, memory consolidation, and overall well-being
The Solution
Instead of relying on abrupt alarms that jolt you awake, the ideal solution is to wake up during the lightest stage of sleep closest to your desired wake-up time. Sleep stages are typically studied using advanced methods like polysomnography (PSG), industry standard for sleep research. PSG combines measurements from an electroencephalogram (EEG) to track brain waves, an electrooculogram (EOG) to monitor eye movements, and an electromyogram (EMG) to assess muscle activity. While effective, this method requires a specialized environment, expensive equipment, and professional oversight, making it impractical for everyday use. For this project, I proposed a more accessible and cost-effective approach. By using readily available instruments such as heart rate sensors and motion sensors, we can mimic aspects of actigraphy, a less intrusive method for tracking sleep stages. These sensors feed data to a RP2040 microcontroller - The raspberry pi pico, which performs the analysis and algorithmic computations necessary to determine the sleep stage in real time.
Actigraphy
Actigraph device
Actigraph device
The actigraph is a compact and sophisticated wearable device designed to monitor various physiological parameters. It incorporates multiple advanced components to ensure accurate data collection and seamless communication with the rest of the system.
Core Components and Functionality
- MPU6050 Sensor: This gyroscope and accelerometer module detects movement and orientation relative to Earth's gravitational force.
- MAX30102 Sensor: A high-sensitivity pulse oximeter and heart rate sensor. This module measures blood oxygen levels (SpO2) and heart rate
- SEEED XIAO C6 Microcontroller A compact and energy-efficient microcontroller that serves as the processing unit of the actigraph. It gathers data from the MPU6050 and MAX30102 sensors
- 4000mAh LiPo Battery: The actigraph is powered by a high-capacity lithium polymer battery, ensuring extended operation and reliability in wearable use cases.
The SEEED XIAO C6 microcontroller is programmed to manage the sensors and collect readings effectively. Leveraging its Bluetooth Low Energy (BLE) capability, the microcontroller transmits the processed data wirelessly to the Raspberry Pi Pico enclosed in an alarm desk dock. This BLE communication ensures low-power operation and efficient data transfer, making the system ideal for continuous monitoring.
Micro Controller
The system utilizes a Raspberry Pi Pico, a low-cost, high-performance microcontroller board with versatile digital interfaces. Key features of the Raspberry Pi Pico include:
- RP2040 Microcontroller Chip: Designed by Raspberry Pi in the UK.
- Dual-Core Arm Cortex M0+ Processor: Capable of running at up to 133 MHz.
- Memory: 264KB SRAM and 2MB onboard flash storage.
- Wireless Connectivity: 802.11n single-band (2.4 GHz) Wi-Fi, Bluetooth 5.2
The Raspberry Pi Pico functions as the central processor, acting as the "brain" of the entire system. Mounted on the alarm dock, the Pico communicates with the actigraph via its Bluetooth 5.2 capabilities. The Raspberry pi pico is responsible for the following responsibilities.
Data Processing: The Pico receives data wirelessly from the actigraph. Using Python-based algorithms and pre-programmed logic, it analyzes this data to determine the optimal wake-up time
Peripheral Control: A Buzzer that Provides auditory feedback, An LCD Screen that Displays visual feedback, Input Buttons thatEnables navigation and user interaction.
Interfacing with Other Modules The Pico uses UART communication to interface with other system modules programmed in C.
