Can sleep and cognition in healthy adult males be improved using an acoustic device?

On both conditions, participants are required to come into the Monash Sleep Laboratory for two nights. During their entire eight-hour sleep period, they are required to wear the deltaboost device. This is a device which measures EEG using a standard dry electrode. It is fitted by a trained PhD student or staff member, which typically involves cleaning the electrode site as per standard laboratory PSG and putting the headband onto the participant. On the first night, the device is worn so that the participants is acclimated to the device. The headband of the device has three electrodes. These obtain an EEG signal and identify when the participant has reached N3 sleep (when the slow waves dominate). On the experimental night, tones are administered through ear phones during N3 sleep. The volume of the tones is dependent on the individual. The tone volume is set prior to the experiment, and dependent on how sensitive the individual is to noise. The tones are manually set through the DeltaBoost program and saved. The program is then used to write which file and volume the device uses. On the baseline nights, and if the participant is not flagged as sensitive, they will use a tone volume of 0.05-0.30. If the participants do flag as sensitive, the volume is reduced to 0.15. The DeltaBoost program is a custom built script that works with the DeltaBoost device. Sensitivity is determined by running the DeltaBoost data through a MATLAB script, which identifies how easily the participant is aroused by the tones. On night 1, tones are played to the participants through the headphone during the first stage of SWS. The first tone is the lowest volume setting on the device (barely audible). Arousal is monitored on the EEG, and if no EEG-determined arousal is observed, the tone is switched up one level. This continues until an arousal is observed. The preceding tone before the arousal level is then used to determine the maximum volume for the experimental night. This procedure is automated by the DeltaBoost device. The ideal tone is loud enough to invoke an EEG response (e.g., K complex) but not loud to enough to induce an arousal from sleep. The maximum tone is 72dB, which is indicated as 1 on the system. The typical tone is between 0.15 and 0.3. Tones are administered with a frequency of 1Hz during N3 only. On the control night, no tones are administered. Each participant uses the same device for each visit. They are also allocated to their own rooms. The order of the visits are randomised, with a one-week washout in between. Each visit consists of a consecutive 2 night, 2 day stay.